Pests and Diseases

Vegetable gardening has it's challenges, One of which is that many things want to eat your delicious food before you do.

Pests

Plant pests are any creature which poses a threat to your plant, either by eating it, destroying it, or harming it in some way.

Here is a list of all UK Plant pests by the RHS : https://www.rhs.org.uk/advice/plant-problems/pests

Here we'll be focusing on the most common pests for food growers.

Birds

Birds can cause damage to plants at all stages, Pigeons are a particularly troublesome one, Pecking leaves and even uprooting small plants. They target brassicas and peas especially. Preventative measures can be taken using pea and bean netting over targeted plants. Be careful however as birds can get tangled in this netting and die, so be sure to check it regularly.

Slugs and Snails

The most common and more frequently annoying pest, These will eat through anything available, devouring your precious vegetables. Preventative measures such as creating physical barriers of throny or prickly plants such as brambles and roses can work quite well, Nematodes are the best organic solution to slugs and snails, These are applied mixed in a watering can and are parasites that kill slugs and snails before they can multiply and much your veggies. Another organic method is to use beer traps, Which is a container with an open section, laid or sunken into the ground and filled with beer, the slugs and snails venture in and get stuck and drown, cleaning the beer traps is rather griom however. Another organic method is to Simply go out after dark with a torch and look for them, Pick them up and either kill them with secateurs, A kebab skewer or just launch them out of your garden into the distance, Though depending on your situation that might not work and it only really delays them. Another method, Is to keep ducks or chickens, Both of which will patrol your garden and keep populations down.

There is no solid evidence of slug deterrents such as copper properly working, However eggshells work somewhat as slugs / snails dislike walking over it as it's uncomfortable, however it won't stop a hungry slug / snail reaching your veggies.

PLEASE DO NOT USE SLUG PELLETS,THE LITTLE BLUE METALDEHYDE PELLETS CAN BE EATEN BY HEDGEHOGS AND CAUSE EXTREME ILLNESS AND POSSIBLY EXCRUCIATING DEATH!

Aphids

Cats

Cats can cause problems by digging in your prepared veggie beds and using it as a toilet. To them, your nice raised bed looks like a massive litter tray, Deterrents such as half filled clear water bottles, and teabags socked in olbas oil work to deter cats from coming near your beds but only as a temporary solution.

Caterpillars

Brassicas are the favoruite food of caterpillars, Making the ideal environemtn for their growth. the main culprits :

Large cabbage white butterfly (Pieris brassicae)
Small cabbage white butterfly (Pieris rapae)
Cabbage moth (Mamestra brassicae)

Aside from pesticides whic are nto recommended, growig your brassicas under fine netting is the best method for preventing caterpillars, otherwise simply picking off and moving the caterpillars and eggs once they appear can prevent damage somewhat. Organic nematodes can be applied to remove them from infected brassicas.

Foxes

Foxes can cause issues by digging and trampling plants, eating soft berries and the like, unfortunately there is no control measures for them, or deterrents, Foxes will come and go as they please unless there's a solid physical barrier between them.

Grey Squirrels

Squirrels cause damage by digging up bulbs and seeds, scratching the bark of of trees, and eating fruits and veggies.

Unfortunately, there are not many control methods available for squirrels, Netting will foil them slightly and they can legally be trapped in the UK however they'll likely come and go as they please. Scaring devices and Deterrents are availabel commercially, these work on cats too somewhat so are worth a shot if you're a plagued by furry ninjas.

Carrotfly

Carrotflies can make carrots and similar vegatables inedible. The flies themselves are not the issue, rather the grubs, which tunnel within the roots of plants, Control methods invlove preventative planting, such as sowing sparesely to prevent thinning out, as carrotflies target the smell of translanted carrots. Late sown carrots (after mid-May) avoid the first generation of this pest; similarly carrots harvested before late August avoid the second generation. Carrot fly resistant (not immune) plants can be grown, or enviromesh can be used to prevent flies reaching the carrots. Nematodes can be used to control carrotflies. there are no available pesticides.

Blackfly

Blackfly are a species of aphid which like their cousins, Suck sap from plants, leading to reduced vigour and can trasmit diseases to the plant, In severe cases they can lead to eventual plant death. They target soft growing tips, buds and any soft juicy areas of plants with areas where they can hide in. They are occasionally farmed by ants, which eat the sticky excretions of the aphids. Control methods that don't include pesticides are brushing / squishing them, When broad beans are infested pick off thye growing tips, which will reduce their infestation and icrease growth. Where possible, tolerating Aphid infestations will be needed, Pesticides are not recommended for use on foods.

Onion fly

The maggots of onionflies damage bulbs and seedling, causing them to be inedible or die. On older plants outer leaves can yellow and wilt. The onion bulb can be destroyed as the larvae feed within it. This insect is most often encountered in central and eastern England and is most damaging during June and July. There are no insecticides available to home gardeners for controlling onion fly. Growing onions and shallots from sets, rather than seeds, can help plants to survive attacks by the first generation of larvae, ome protection may be gained by using nematodes and insect proof meshes.

Woodlice (Strawberries)

If something has been nibbling hollows into your strawberries, It could be woodlice,

Unfortunately there's not much that can be done control wise,

other than try and make your plants harder to reach for them.

Remove damaged strawberries and compost them.

Diseases

Diseases are Harmful Bacterial, Fungal or Viral infection or disorder in plants.

Here is a link to the RHS guide: Diseases and Disorders :

https://www.rhs.org.uk/Advice/Plant-Problems/Diseases-Disorders

Damping Off

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/profile?pid=151

Damping off is a Fungal Disease that affects Seedlings. I causes the Seedlings to collapse and be covered in in a mass of 'furry' white fungal growth. This is mainly a problem when starting seedlings indoors, When conditions are too humid and damp.Damping off can affect most seedlings, particularly under conditions of high humidity, poor air circulation and if seed is sown too thickly. preventative methods include disinfecting reused trays and pots, Sowning thinly to prevent crowding, And water using Mains water as It is more likely to be fungi free. Do not overwater and keep ventiliation high. There are no Chemical controls for damping off.

Broad Bean Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=112

Broad bean rust is one of the most common fungal diseases of broad bean leaves. The fungus causes small, dusty, dark brown spots surrounded by a pale yellow halo on leaves and stems. Broad bean rust can cause defoliation. Preventative measures include spacing plants to improve airflow and ventiliation, and removin infected material as soon as it appears.

There is no Chemical control for this Fungal Disease.

Apple Canker

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=63

Apple canker is a fungal disease causing disfiguring and sunken patches of dead bark on the branches of apple and some other trees. Infections often begin at wounds or buds. The infection can girdle and kill off stems. Control methods involve cutting away infected sections, and planting canker resistant varieties is recommended. There are no chemical controls for Apple canker.

Cucumber Mosaic Virus (CMV)

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=143

This one of the most common plant viruses, causing yellow mottling, distorted leaves and

stunted growth in a wide range of garden plants, not just cucumbers. Apart from cucumbers and other cucurbits, it also attacks spinach, lettuce and celery. Destroy suspect plants promptly to reduce the risk of transmission. Keep the garden weed free. Groundsel and chickweed are particularly likely to harbour CMV, It is mainly transmitted by Aphids but can be transfered by handling and tools, Keep tools clean and Choose resistant varieties. There are no Chemical controls to help with CMV.

Fireblight

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/profile?PID=160

Fireblight is a bacterial disease that kills the shoots of apples, pears and related ornamentals,

giving the plant the appearance of having been scorched by fire.

It does not infect stone fruits, Blossoms wilt and die at flowering time,

A slimy white liquid may exude from infections in wet weather,

Shoots shrivel and die as the infection spreads down the inner bark.

Prune out and burn infections promptly, peeling back the bark to reveal the reddish-brown staining and cutting back 30cm (1ft) to healthy wood in smaller branches, 60cm (2ft) in larger ones. Wipe pruning tools with disinfectant between cuts to avoid spreading the bacteria. Remove secondary, late blossoms before they open. There is no Chemical control for Fireblight.

Gooseberry Mildew

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=739

This is one of a group of fungi causing powdery mildews on a wide range of plants and is the most serious disease of gooseberries. From early summer, symptoms appear on gooseberry bushes as:

Powdery grey-white fungal patches on the leaves, which later turn brown,

Mildew on the fruits turns brown as it ages,

Young shoots are stunted and twisted at the tops, and die back.

The fungal growth on the berries can be rubbed off, and the gooseberries are edible, so there is no need to waste the crop if many of the fruits are affected. However, even after this laborious process the diseased berries will turn brown when cooked.

Pruning in open formation to improve are circulation, The fungus overwinters within the buds and on the shoots, and (with blackcurrants in particular) on fallen leaves.

It is therefore essential to prune the bushes by removing and disposing of the ends of affected shoots as soon as they are seen, as well as disposing of all fallen leaves in autumn. There are resistatn cultivars to choose from.

Chemical control: SB Plant Invigorator, Resolva Natural Power Bug and Mildew Control, RHS Bug and Mildew Control, Ecofective Bug & Mildew Control and the Ecofective ‘Defender’ range contain a blend of surfactants and nutrients and can be used on any edible or ornamental plants, with no harvest interval. They have a physical mode of action and may be used against powdery mildews.

Brassica Downey Mildew

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=105

Downy mildew of brassicas is a foliage disease causing whitish, fuzzy patches on the undersides of leaves and yellow discolouration on the top. It affects seedlings and mature plants.

You may see the following symptoms:

On seedlings: The entire plant becomes covered in a whitish coating of the pathogen and dies rapidly
On larger plants: Yellowish patches of discolouration on the upper surfaces of leaves, often angular and limited by veins. On the corresponding lower surface is a fuzzy whitish outgrowth of the pathogen. Eventually, the affected tissues die, shrivel and may drop out
On cauliflower curds and radishes: Leaf damage may be accompanied by internal browning of the cauliflower curds and radish flesh

Plant brassicas with wider spacings to encourage air flow, Remove wild/weed host plants to reduce any chance of cross-infection, Remove infected material promptly and destroy, to avoid contaminating the soil with resting spores.

There are no chemical controls for Brassica Downey Mildews.

Tomato Leaf Mould

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/profile?pid=468

Leaf mould can develop rapidly to cause significant yield loss in greenhouse-grown tomatoes. It is rarely seen on outdoor crops. Symptoms include:

lower leaves are generally attacked first
Yellow blotches develop on the upper leaf surface
A pale, greyish-brown mould growth is found on the corresponding lower surface
Where the disease is severe the mould growth may also be found on the upper surface
Heavily infected leaves turn brown and shrivel, but do not fall
The grey mould fungus, Botrytis cinerea, may colonise affected leaves, masking the leaf mould. The spores of grey mould are more powdery, and the fungal growth more fluffy than that of leaf mould
Flowers and fruit may be attacked, but this is less common than leaf infection
Affected plants lack vigour and yield poorly

Preventative meaure include; Prevent wetting leaves when watering, Providing ample ventiliation, try to avoid temperatures over 21 degrees C, Prune off lower leaves to improve air circulation. There are nno Chemical copntrols available for Tomato Leaf mould.

Tomato Viruses

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=250

Many viruses affect tomatoes causing mosaic patterns on leaves, leaf distortions,

stunted growth, bronzing or marbling patterns on the fruit. The most common tomato viruses are:

Tobacco mosaic virus (TMV)
Tomato mosaic virus (ToMV)
Tomato spotted wilt virus (TSWV)
Pepino mosaic virus (PepMV)
Cucumber mosaic virus (CMV)

You may see the following symptoms:

Stunted growth and reduced yield are common symptoms, especially when several viruses are present
Mosaic patterns of lighter green on the leaves (TMV, ToMV, CMV, PepMV)
Fern leaf, where the leaf blade is reduced in size to give a fern-like appearance (TMV, CMV, PepMV)
Brown streaked leaves (TMV)
Young leaves curl downwards and become bronzed (TSWV)
The leaf surface appears distorted and bubbly (PepMV)
Dry set, when fruit fail to set (TMV)
Fruit develop a bronzed, patchy appearance (TMV, ToMV)
Fruit ripens unevenly with pale patches or marbling (TSWV, PepMV)

Control methods: Remove plants with symptoms promptly, After handling infected plants, wash hands and tools in hot soapy water. As an additional precaution, sterilise tools in the disinfectant, Avoid growing other susceptible plants in close proximity

Varieties with claimed resistance to TMV include ‘Cherry Wonder’, ‘Cumulus’, ‘Dombito’, ‘Dona’, ‘Estrella’, ‘Ida’, ‘Nimbus’, ‘Piranto’, ‘Shirley’ and ‘Sonatine’

Apple and Pear Scab

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=81

Apple scab and pear scab are two fungal diseases that cause dark, scabby marks on the fruit and leaves of apples, pears and some other ornamental fruits. They are so similar that they are dealt with in the same way. You may see the following symptoms:

On leaves: Patches of olive-green spots or blotches appear, which are initially velvety as they release airborne spores, and then darkening. Affected leaves often fall prematurely.

On twigs: Infections cause blistering and cracking that can provide an entry point for the apple canker pathogen.

On fruit: Brown or black scabby blotches develop. As the fruit enlarges, these can restrict expansion of the skin, leading to distortion and cracking. Light attacks only blemish the skin and eating quality is hardly affected (though the disease is commercially very serious, because growers cannot easily sell scabby fruit). However, if the fruits crack as a result of scab they become prone to fruit rots and will not store well.

Control methods are: Pruning out twigs that are blistered, and disposing of fallen leaves and infected fruit will reduce the amount of the fungus available to start infections in the next growing season. Unfortunately, this can be of limited value unless the trees are isolated, because the spores can be blown for long distances. There are several Resistantn varieties, There is no Chemical Control for Apple and Pear Scab.

Brown Rot

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=114

Brown rot is a fungal disease of apples, pears, plums, cherries and other fruit and ornamental trees, causing a brown, spreading rot in fruit. It is caused by the same fungi that cause blossom wilt of the flowers and fruit spurs.

You may see the following symptoms:

Brown rot in the fruit, spreading out from wounds, especially those made by birds, codling moth and apple scab infection
Affected fruit either fall, or remain hanging on the tree in a mummified state
Buff-coloured pustules of the causal fungi on the fruit surface, often in concentric rings. Usually seen under wet conditions
At flowering time the same fungi cause blossom wilt, where blossoms and leaves on fruiting spurs turn brown and shrivel
Severity varies greatly from year to year, depending on weather conditions at flowering.

Minimise carry-over of the pathogens by removing and disposing of all brown rotted fruit promptly. To dispose of fruit, you can bury them at least 30cm (1ft) below the soil surface. Do not allow rotted fruit to remain on the tree.

Brown rot infects through wounds, especially those caused by birds, so if possible, net to reduce bird damage.

If practical, prune out and burn infected spurs and blossoms to reduce the amount of fungus available to infect fruit.

The plums ‘Czar’, ‘Jefferson’, ‘Ontario’ and ‘President’ have some resistance. There is no Chemical control for Brown Rot.

Mint Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=220

Mint rust is a common fungal disease of garden mint, but also affects marjoram and savory. The fungus causes dusty orange, yellow and black spots on leaves. You may see the following symptoms:

Pale and distorted shoots in spring
Dusty orange pustules on the stems and leaves. These may be followed by dusty yellow or black pustules
Large areas of leaf tissue die and plants may lose leaves

Remove affected plants promptly before the black resting spores are formed and contaminate the soil. In the case of garden mint it is also necessary to remove infected rhizomes. In an infected bed, try to locate any uninfected stems and carefully dig these out and move to another location in an attempt to start a new, healthy colony.

There are no Vhemical controls for Mint Rust.

Sweet Pea Viruses

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=248

Many viruses affect Lathyrus spp. (sweet peas) causing streaked flowers, mottled leaves,

stunted growth and dead patches on leaves.

These are In the UK:

Pea enation mosaic virus (PEMV)
Bean yellow mosaic virus (BYMB)
Pea mosaic virus (PMV)
White clover mosaic virus (WCMV)

Symptoms may be seen when the plants are growing from spring until late summer.

You may see the following symptoms:

Mottled and white-streaked leaves
Dead spots or patches on leaves
Colourless veins
Translucent patches on leaves
‘Breaks’ (white streaks) on flower petals
Stunting and loss of vigour

Control methods:

If infection is suspected, remove infected plants and destroy, there are no treatments for virus infection
Consider buying good quality seed, rather than plants, as most viruses are not seed borne
Remove legume weeds such as clover which may harbour viruses
Clean pruning tools with garden disinfectant between plants
Sweet peas, particularly cordon grown ones, are subject to virus-like symptoms, so check that growing conditions are being met.

There are no Chemical Controls for Sweet Pea Viruses.

Pear Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=236

European pear rust is a fungal disease of pear trees, causing bright orange spots on the leaves. It also affects junipers, causing perennial canker-like swellings on the branches.

Symptoms include; Bright orange spots on the upper leaf surface.

As summer progresses brown, gall-like outgrowths develop on the corresponding lower leaf surface.

Fruit may be affected, but this is much less common.

In mainland Europe the fungus can also cause perennial cankers (lesions in the bark) on the branches, which can be damaging to young trees in particular. So far, however, these have not been common in the UK.

Control Methods include:

Careful pruning of junipers to remove rust infections from the stems, or simply removing whole plants from the vicinity of pear trees will reduce the likelihood of infection, but note that the spores are airborne over quite long distances.

Removal of leaves on heavily infected pear trees may do more harm than good. Prune out any branch cankers seen on pear trees. There are No Chemical controls for pear rust.

Potato and Tomato Blight

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=217

Potato and tomato blight, properly called late blight, is a disease of the foliage and fruit or tubers of tomatoes and potatoes, causing rotting. It is most common in wet weather. You may see the following symptoms:

Potatoes; The initial symptom of blight on potatoes is a rapidly spreading, watery rot of leaves which soon collapse, shrivel and turn brown. During humid conditions, a fine white fungal growth around the edge of the lesions on the underside of the leaves.

Brown lesions may develop on the stems.

If allowed to spread unchecked, the disease will reach the tubers. Affected tubers have a reddish-brown decay below the skin, firm at first but soon developing into a soft rot as the tissues are invaded by bacteria. Early attacks of blight may not be visible on tubers, but any infected tubers will rot in store.

Tomatoes; The symptoms on tomato leaves and stems are similar to those on potatoes.

Brown patches may appear on green fruit, while more mature fruits will decay rapidly.

Control Methods:

Infected material should be deeply buried (more than 45cm deep), consigned to the green waste collection or, ideally, burned rather than composted.

Earthing up potatoes provides some protection to tubers, Early-harvested potatoes are more likely to escape infection.

Gardeners are able to access forecast warnings of when blight is active, or when there have been confirmed cases, in their region (visit the Fight Against Blight website)

Picking off leaves or leaflets when just a few are affected may slow down the progress of the disease very slightly, but will not eradicate the problem. Use the tubers from blighted crops as soon as possible, checking any stored tubers regularly for decay.

Operate a rotation to reduce the risk of infection, ideally of at least four years, Destroy all potatoes left in the soil, and any waste from storage, before the following spring.

There are no Chemical control for blight.

Silver Leaf

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=245

Silver leaf is a fungal disease of the wood and leaves of some trees, especially plums, apples, apricots and cherries. The fungus infects the wood through wounds and causes a silvering of the leaves followed by death of the branch.

You may see the following symptoms:

On leaves: Leaves develop a silvery sheen, especially noticeable in plums but less so in other trees. Following the appearance of the silvery sheen, affected branches die
On branches: When affected branches are cut across, an irregular dark stain may be seen in the centre, not necessarily corresponding to the heartwood. On older dead branches, bracket-shaped fungi appear. These have a whitish woolly upper surface and a purple-brown lower surface with fine pores

Control Method:

Since the fungus produces most of its infectious spores in autumn and winter, ideally carry out routine pruning of susceptible plants in summer. Not only are there fewer spores at this season but pruning wounds, the main point of entry for the spores, heal more quickly.

Where silver leaf develops the affected branch should be removed as soon as possible, certainly before the fungal fruiting bodies appear. The branch should be cut off, where possible, at a point 10-15cm (4-6in) beyond the area where the staining in the internal tissues ceases. Cutting equipment should be disinfected regularly. Dispose of the pruned material immediately, as fruiting bodies will still form if it is left lying around.

Canker

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=86

Bacterial canker is a disease of the stems and leaves of Prunus, especially plums and cherries, but also apricots, peaches and ornamental Prunus species. It causes sunken patches of dead bark and small holes in leaves, called ‘shothole’.

You may see the following symptoms:

On stems and spurs: Sunken, dead areas of bark develop in spring and early summer, often accompanied by a gummy ooze. If the infection spreads all round the branch it will die rapidly. However, it should be noted that gum production (gummosis) from the bark of Prunus species is actually quite common, and in the absence of dead, sunken bark is likely to have resulted from causes other than bacterial canker, for example physical damage or environmental stresses
On emerging shoots: Shoots may either fail to emerge, or start to grow normally in spring before dying back rapidly. In severe cases this may affect a large percentage of shoots on a tree. Note that shoot dieback can also be caused by the fungal disease blossom wilt
On leaves: Small brown spots appear, which are often round and eventually fall out to leave holes – as if the leaf had been hit by shotgun pellets, leading to the popular name of ‘shothole’

Control Methods:

Where possible, carry out all pruning in July or August when tissues are most resistant. This is also the best time to prune in order to minimise the risk of infection by spores of the fungus causing silver leaf disease. Cut out all cankered areas, pruning back to healthy wood and painting promptly with a wound paint to protect the wound from re-infection. Details of wound paint products can be found in the 'Fungicides for gardeners' document below. Burn or landfill the prunings.

The cherries ‘Merton Glory’, ‘Merton Premier’, ‘Merla’ and ‘Merpet’ and the plums ‘Marjorie’s Seedling’ and ‘Warwickshire Drooper’ have some resistance. There are no Chemical controls for Canker.

Broad Bean Chocolate Spot

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=89

Chocolate spot is one of the most common fungal diseases of broad beans. The fungus causes dark, chocolate-coloured spots on all parts of the plant.

You may see the following symptoms:

Small round, red-brown spots on all parts of the plant.

Under favourable conditions these spots expand aggressively, turn a darker, chocolate-brown colour, and leaves shrivel.

Stem infections may cause the plants to collapse.

Control Methods:

Maximise air flow around the plants by wider spacing and avoid damp, humid sites.

Destroy infected plant material at the end of the season.

Eliminate common vetch from the vicinity.

Avoid using seed from infected plants.

There are no Chemical controls for this disease.

Onion White Rot

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=226

White rot is a serious fungal disease of onions, garlic and leeks causing yellowed, wilting foliage and decay of the roots and bulb. It may persist in the soil for many years.

You may see the following symptoms:

Above ground, the first symptom is yellowing and wilting of the foliage, especially in dry weather
Under wetter conditions the plants may not wilt, but will become loose in the soil
Below ground, the pathogen rots the roots and then invades the bulb
White fluffy fungus growth appears on the base of the bulb and later this becomes covered in small, round, black structures

Control methods:

Stromatinia cepivora is effectively impossible to eliminate once it has been introduced and the long survival period makes crop rotation impractical. It is therefore extremely important to avoid introduction to previously clean sites. It is transported in contaminated soil, for example on tools or on muddy footwear. Take particular care in areas where cross contamination can occur easily, for example on allotments.

Potato Black Scurf and Stem Canker

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=744

Black scurf is a fungal disease that causes black patches on the surface of tubers that can be rubbed off. Although unsightly it is not destructive, but infected seed potatoes can lead to plants with stem cankers.

Black scurf is easily recognised:

Raised, hard, black patches, irregular in size or shape, on the surface of the tuber. These are readily rubbed/scraped off
Brown strands of fungal material called mycelium can sometimes be seen around the black scurf with the aid of a magnifying glass
The scurfs themselves are in fact compact masses of mycelium

The fungus can also cause a symptom known as stem canker on potato sprouts (new shoots) and stems:

Sunken, brown lesions develop on the sprouts before they emerge from the soil
In severe cases the tip of the sprout is killed. It often shoots again from lower down, but emergence is delayed
Rough, brown, sunken patches develop on the stem, below soil level
If these girdle the stem then stunting and wilting often results, sometimes with the production of small, green, aerial tubers in the junction between the stem and leaf stalk

Control methods:

Use seed tubers free of substantial infection
Practise crop rotation
Avoid excessively early planting, use seed that has been sprouted (chitted) prior to planting, and water plants in dry periods
Where black scurf and stem canker has been a problem previously, consider planting into shallower ridges (to help speed emergence of the shoots from the soil)
Early lifting will reduce the numbers of black scurfs that form on the tubers

There are no chemical controls for this disease.

Potato Blackleg

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=223

Potato blackleg is a common bacterial disease of potatoes, which causes black rotting at the stem base. Initial infections cause stunted growth and yellowing stems. You may see the following symptoms:

As early as June, the stems of potato plants appear stunted and pale green or yellow
Leaves at the top of affected stems may be small, stiff and have margins curled inwards
At ground level, these affected stems appear black and rotted
If tubers form, the flesh may be grey or brown and rotten

Control Methods:

There is a number of control measures that do not require chemicals:

The most important control measure is prompt removal and destruction of infected plants as soon as symptoms are noticed and before the disease has time to spread
Commercially produced seed has very low (but not zero) levels of infection. Gardeners who save their own seed should be particularly careful that it is uninfected. Dry storage of seed or ware (grown for consumption) potatoes will minimise the risk of spread in storage
The disease thrives in warm, damp conditions so improve poorly drained sites
Try to lift crops during dry weather
Rotation is important, since the bacteria may survive over winter in ground where potatoes were previously grown, albeit at a low level. Rotation also reduces the risk of infection arising from infected volunteer potatoes (potato plants that grow from tubers inadvertently left in the ground from the previous year's crop)
Choose resistant cultivars. AHDB Potatoes produces the British Potato Variety Database, which lists resistant varieties including ‘Charlotte’, ‘Pixie’, ‘Saxon’ and ‘Vales Sovereign’.

There are no Chemical controls for Potato Blackleg

Potato Scab

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=230

Common scab and powdery scab are bacterial and 'fungal' diseases of potato skins, causing rough, scabby patches.

You may see the following symptoms:

Common scab: Raised, rough patches of skin on the tuber surface
Powdery scab: Irregular brown raised areas or depressions, often with papery margins, on the surface of tubers. These areas contain masses of dusty brown spores.

Control Methods:

Select seed carefully and avoid planting seed potatoes that have visible signs of scab. Legislation controls the amount of infection allowed in seed, but low levels are permitted
To control common scab, do not allow the soil to become dry during tuber development. Raise organic matter levels to improve water retention. Water the developing crop if necessary, starting two to three weeks after plants emerge and continuing for about four weeks, applying 20 litres per sq m (4 gallons per sq yd)
Common scab is worse on alkaline soil, so liming the soil to prevent club root of brassicas will predispose to common scab in potatoes. Apply lime after the potato course of the rotation
Choose resistant cultivars. ‘Accent’, ‘Arran Pilot’, ‘Juliette’, ‘Golden Wonder’, ‘King Edward’, ‘Pentland Crown’ and ‘Pentland Javelin’ show some resistance to common scab. ‘Desiree’, ‘Hermes’, ‘King Edward’, ‘Pixie’ and ‘Sante’ show some resistance to powdery scab.

There is no Chemical control to Potato Scab.

Raspberry Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=775

Rust disease on raspberries is a fairly common problem, and can cause concern when high levels of the disease are present. However, whilst it can be a very conspicuous disease, affected plants still usually give a satisfactory yield of fruit.

You may see the following symptoms:

In spring and early summer: clusters of slightly raised, yellow pustules appear on the upper leaf surface, usually beginning on the bottom leaves
As summer progresses: the pustules described above become less conspicuous, but numerous tiny orange pustules begin to be produced on the lower leaf surface, often with small yellow spots on the corresponding upper surface
Large numbers (scores, or even hundreds) of these ‘summer spore’ pustules may be present on a single leaf
Severe infection may lead to premature shedding of leaves
In late summer and autumn: the orange pustules are gradually replaced by black ones, containing overwintering spores.

Control Methods:

If the yellow pustules can be spotted in spring, and just a few leaves are affected, then picking these off may slow the spread of the disease
If large numbers of leaves are affected, however, removing them will do more harm than good
Collect up and dispose of any leaves that fall prematurely, together with the rest of the leaves as they fall in the autumn
Ensure that the canes are not too crowded as this will lead to poor air circulation, prolonged leaf wetness, and higher disease levels
Feed plants adequately to ensure good vigour, but don’t overdo it as this will produce excessively soft growth that is more prone to attack

There are no Chemical controls for Raspberry Rust.

Currant and Gooseberry Spot

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=741

This is a fungal disease that attacks the foliage of currants (black, red and white) and gooseberries in summer, and can be troublesome in some seasons and gardens.

The first symptoms appear on the leaves in early summer (usually about June):

Leaves become spotted with very small, dark brown or black spots
Later, the spots become more numerous and often coalesce so that large areas of the leaves turn brown
Large numbers of minute fungal spores form in fruiting bodies on these spots and may sometimes be visible as small droplets on the surface of the spots
When the disease is severe, the leaves fall and the bushes may become defoliated by early July
Sometimes the fruit shrivels before ripening

Control Methods:

Rake up and dispose of (bonfire, consigning to green waste or burying deeply) fallen leaves in order to prevent spring infection
Diseased bushes should be well fed (Growmore at a rate of 70g per sq m or 2oz per sq yd) – where severe defoliation has occurred, it is probably worthwhile spraying developing leaves with a foliar feed such as Maxicrop, Miracle-Gro or Phostrogen the following season to enhance early growth
Mulch bushes grown on light soils with a 5-7cm (2-3in) layer of garden compost or leafmould to conserve moisture, and water in dry periods before the soil dries out completely. Rotted manure is ideal for blackcurrants, which have a higher nutrient requirement
Bushes on light soils may need watering every 14 days in dry periods in summer

There are no Chemical Controls.

Grey Mould

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=165

Grey mould, caused by the fungus Botrytis cinerea, is a very common disease, causing a soft decay of plant tissues accompanied by a growth of fuzzy grey-brown mould. It affects many plants, especially those grown under glass where conditions are humid. It is also a common disease of soft fruit, such as gooseberries, strawberries and grapes.

You may see the following symptoms:

Under humid conditions fuzzy grey-brown mould grows on decaying buds, leaves, flowers or fruit
If humidity is low, infections may be contained within discrete spots, but if it is high they can spread rapidly
Above-ground parts of many plants, particularly buds and flowers, shrivel and die
Small black seed-like structures form on infected material (these are often overlooked)
On bush and cane fruit, particularly gooseberries, Botrytis infection kills branches, but the fuzzy grey mould is seldom evident
On strawberries, grapes and sometimes other fruits, Botrytis infection leads to a soft brown rot, often as the fruit is ripening

Control Methods:

Hygiene is very important, especially under glass. Remove dead and dying leaves, buds and flowers promptly
Do not leave dead plant material lying around
Reduce humidity by improving ventilation and do not overcrowd plants.

There are no Chemical controls.

Downey Onion Mildew

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=743

Onion downy mildew is a disease of onions and related crops that damages foliage and bulbs, resulting in loss of yield or even a complete failure of worthwhile bulbs to form.

Be alert for the following symptoms:

The affected leaves turn yellow and die off from the tip downwards
In moist conditions a white, and later purplish mould develops on affected parts of the leaf
This, in turn, is commonly followed by darker mould growth of other leaf-infecting fungi
Bulbs can also be infected and often sprout prematurely or shrivel in store

Control Methods:

Avoid overcrowded crops, damp conditions and sheltered sites and maintain good weed control to ensure airflow through the crop
Do not compost infected material
It is recommended to remove and dispose of affected plants and avoid replanting with onion or shallots for five years
It is important not to allow any bulbs to remain in the soil from year to year. The fungus remains dormant in infected bulbs, producing spores in the spring which spread the disease to newly sown plants
Any soft, mouldy or otherwise suspect onion sets should not be planted
Onions sown in late summer for over-wintering can carry the disease from year to year
Onion sets for over-wintering, planted in late September, should be less vulnerable to infection and acting as a source of the disease for crops sown or planted the following year
However, if possible separate over-wintered crops as much as possible from spring ones
Similarly, perennial onions should be separated from other onion crops in the vegetable garden

Leek Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=214

Leek rust is a common fungal disease of leeks and garlic, but also affects onions and chives. The fungus causes bright orange, raised spots (pustules) on leaves.

You may see the following symptoms:

On leaves: Bright orange pustules on both sides of infected leaves. These are initially enclosed by the surface tissues of the leaf, but break open to release dusty, orange, airborne spores
Severe attacks may cause leaves to shrivel prematurely and will reduce vigour

Control methods:

Infection is worse on nitrogen-rich soils with low potassium, so take care with fertiliser applications
Do not crowd plants, as this raises humidity and increases the likelihood of infection
Dispose of all plant debris at the end of cropping

There are no Chemical controls.

Raspberry Cane Blight

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?PID=266

Raspberry cane blight is a common and serious fungal disease of raspberries, causing extensive die-back of canes.

You may see the following symptoms:

During summer, leaves on fruiting canes wither and the canes die
The bases of the canes become dark brown, and the bark may split. The wood becomes very brittle so that the canes snap off easily at the base
Tiny, black fungal fruiting bodies, just visible to the naked eye, are produced on the infected wood

Control Methods:

Handle canes carefully to avoid unnecessary damage
Ensure that they are well spaced so that air circulates and the canes dry out quickly after rain or heavy dew
Avoid plant stress by providing appropriate soil conditions, for example by improving drainage on heavy soils and mulching around the canes to prevent the soil drying out during periods of drought
Prune only during dry periods
Where the disease develops, cut out and dispose of any affected canes. Cut back to below soil level and disinfect the secateurs between cuts
Do not plant raspberries or strawberries in an old raspberry bed without first changing the soil
The raspberry cultivar ‘Julia’ has some resistance to cane blight

There are no Chemical controls.

Raspberry Spur Blight

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=267

Raspberry spur blight is a fungal disease of raspberries, causing purple patches on canes. It rarely kills the plants, but can reduce yield severely by weakening the canes and killing buds.

You may see the following symptoms:

Conspicuous purple patches on new canes in late summer, centred around the buds. They increase in size, spreading up and down the cane from the point of infection
As autumn and winter progress the patches become less distinct, fading to a pale grey or silvery colour. Fruiting bodies of the causal fungus may be visible as tiny black dots on the affected areas
Many of the buds on canes, infected the previous year, fail to grow in spring or produce weak shoots that soon die. These canes appear bare and unthrifty compared to their healthy counterparts

Control Methods:

Avoid overcrowding by thinning out any young canes that are not required. This should be done as early in the spring as possible
Avoid the over-application of nitrogen
If spur blight develops, cut out and dispose of badly affected canes
Choose resistant cultivars. The cultivars ‘Glen Lyon’, ‘Glen Moy’, ‘Glen Rosa’, ‘Julia’, ‘Leo’ and ‘Malling Admiral’ have some resistance to spur blight

There are nno Chemical controls.

Bean Rust

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=559

Beans can be affected by a fungal disease called rust. Heavy attacks may reduce plant vigour and hence yield but, thankfully, the attack often develops too late to have a serious effect.

You may see the following symptoms:

Initially, pale, raised spots appear on the upper leaf surface, corresponding to small white pustules on the lower surface. As summer progresses, tiny brown and then black pustules form on the lower leaf surface, often in great numbers. The black pustules also form on the upper surface. Pods may also be affected
Heavily infected leaves turn brown and die, and severely affected plants may be stunted. It can also lead to shrivelling and shedding of leaves

Control Methods:

Thin out dense growth on bean crops to help reduce humidity and thus the risk of infection
Picking off affected leaves as soon as symptoms are seen should check the development of the disease. Symptoms tend to develop on older leaves first
Dispose of (bin or burn) any severely affected plants as these will produce huge numbers of spores
Clear up and dispose of all debris (including fallen leaves) at the end of cropping
Do not save seed from rust-affected crops

There is no Chemical control.

White Blister

Here is a link to the RHS guide: https://www.rhs.org.uk/advice/profile?pid=751

White blister is a foliar disease that may be found in the garden on a limited range of ornamentals, vegetables and weeds. It can reduce plant vigour, and sometimes also causes distorted growth.

You may see the following symptoms:

Pale leaf spots form, which eventually develop into blister-like white pustules releasing huge numbers of tiny, powdery spores
The pustules are usually found on the underside of the leaf, and may develop singly or in concentric rings
There is often abnormal pigmentation (e.g. purpling) surrounding the affected area
Other aerial parts, such as stems, flowers and seed pods can also be attacked
Affected plant parts are often distorted, resulting in bulges or sunken pits on leaves, curved stems and abnormally-shaped flower heads or seed pods. Brussels sprout buttons develop conspicuous protrusions where white blister is present
Vigour is reduced and severely-affected plant parts can shrivel and die

Control Methods:

Remove affected plant parts, and dispose of severely infected plant material
Avoid close spacing of plants, which encourages high humidity and infection
Remove weed hosts of the disease (although see the comment under ‘Biology’ regarding species of Albugo and Pustula)
Crop rotation may help to reduce the incidence of the disease
Seed catalogues list cultivars with resistance or tolerance to white blister including Brussels sprout ‘Bridge F1’ listed as resistant, and 'Doric F1', ‘Exodus F1’, ‘Maximus F1’ and the broccoli cultivar ‘Green Magic’ noted as having good tolerance

There is no Chemical control.

Disposing of diseased material

Here is a link to the RHS guide: https://www.rhs.org.uk/Advice/Profile?PID=612

A key part of disease control within a garden is good hygiene. Infected material from plants in the garden and allotment should be removed promptly and disposed of carefully in order to limit the spread of disease.

To reduce problems:

Remove infected leaves from herbaceous plants and vegetables as soon as they are spotted
Prune woody plants in dry conditions and, in the case of Prunus, only in summer when fungal diseases such as silver leaf are least prevalent
Disinfect tools with a garden disinfectant (used as directed by the manufacturers) after pruning material affected by viruses and other pathogens carried in sap, such as bacterial canker
Avoid spreading soil-borne diseases such as club root, Phytophthora root rot or honey fungus by cleaning boots, tools and equipment after digging, working or walking on contaminated soil. In such cases, don't move soil round the garden
Ensure all infected leaves of deciduous plants, such as roses with black spot, are gathered up in winter and disposed of before vulnerable new growth emerges
Mulch around the base of shrubs in early spring to bury remaining spores
Remove stumps and roots of trees affected by root diseases such as honey fungus. Where digging out is not possible, stump grinding should be undertaken and the grindings should be collected up and sent to landfill
Remove weeds that can act as a reservoir for infection; groundsel hosts some leaf rusts, for example
Clean greenhouses, tools, pots and trays thoroughly in winter, to reduce problems such as damping off

How to dispose of diseased material

It will be necessary to use a range of disposal methods, depending on the type of material and the disease:

Home composting
Although compost bins rarely reach temperatures sufficient for killing pathogens, they are suitable for disposing of material infected by some less-persistent diseases. Common foliar fungal diseases such as powdery mildews and rusts can not usually survive for long once the plant material has fully degraded. This is especially true if the infection has been caught early, before the pathogen has had time to produce resilient spores or structures
Green waste
Council composting facilities should reach temperatures capable of killing most diseases. Although transport and collection makes this option less sustainable than home-composting, many gardeners may be more comfortable sending infected material out of the garden. Some councils vary in what they are prepared to accept – thick branches and large volumes of rotten fruit may not be, for example. If in doubt, check with your local authority
Burial
This is a simple, sustainable way of handling some diseased material on site; for example, leaves infected with foliar diseases such as black spot and fruit suffering from rots such as brown rot. Find a site in bare ground between shrubs or in a vegetable garden and bury material at least 30cm (1ft) deep so that it will not be unearthed by cultivation or mammals. Do not bury material infected by soil-borne diseases such as club root and sclerotinia or any woody material that will be slow to break down
Bonfires
Dry, woody material can be burnt in gardens that are large enough to have a safe bonfire or incinerator. This is ideal for branches affected by canker and fireblight and for woody roots infected with honey fungus. Traditionally, annual autumn bonfires would have been the way of disposing of uncompostable material, but do bear in mind that leaving diseased material stacked until bonfire night can be unhygienic. Bonfires create pollution and may also annoy neighbours. They should be conducted when wind and weather mean that smoke will not enter houses or inhibit others from enjoying their garden. Here are some government guidelines on bonfires in smoke control areas.
Household waste
Plant material such as rotten bulbs and tubers, collapsed seedlings in contaminated compost and small woody prunings can be thrown away in the household waste. From here they will be sent to landfill sites to be buried deeply in a lined and sealed environment. Consider this only when other methods are not appropriate, as landfill space is in short supply and biodegradable material in landfill releases methane (a greenhouse gas contributing to climate change)
Council refuse site
Where burning is not possible, woody material and rootballs may need to be taken to the tip/recycling centre. It is a requirement to deposit these with general waste as they are usually too large for shredding for compost

Disorders

Here is a link to the RHS guide:

Pests and Diseases

To reduce problems:

How to dispose of diseased material

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