Diseases are microbial; Pests anything bigger!
Diseases: three main pathogenic microbes: virus, bacterial, fungal
Fungal diseases spread through the air; 1 cell organism
Most vegetable diseases are caused by fungi. They damage plants by killing cells and/or causing plant stress. Sources of fungal infections are infected seed, soil, crop debris, nearby crops and weeds. Fungi are spread by wind and water splash, and through the movement of contaminated soil, animals, workers, machinery, tools, seedlings and other plant material. They enter plants through natural openings such as stomata and through wounds caused by pruning, harvesting, hail, insects, other diseases, and mechanical damage.
Black spot – Fungal leaf spot attacks lettuce and can also occur on brassicas and other vegetables including such as cabbage, cauliflower, Chinese cabbage, broccoli, Brussels sprouts, kohlrabi, kale, turnip and rutabaga.
Damping off – Damping off is a disease of seedlings caused by several different fungi and fungus-like organisms. This disease causes emerging seedlings to collapse, often submerged in a mass of white fungal growth. It is particularly a problem when sowing seed indoors or under glass.
Black Leg – Potato blackleg is caused by the bacteria Erwinia carotovora subspecies atroseptica. Bacteria remain dormant in seed potatoes and become active when conditions are right, making it both unpredictable and brutal. Like with cole crop blackleg, there are no sprays or chemicals that can stop this blackleg, only cultural controls will destroy the disease. Blackleg symptoms in potatoes typically involve very inky black lesions that form on infected stems and tubers. Leaves above these spots will yellow and tend to roll upwards. If the weather is very wet, affected potatoes may be slimy; in dry weather, infected tissue may simply shrivel and die.
Cole crop (brassicas) blackleg appears first on young plants as small brown lesions that expand into circular areas with gray centers covered in black dots. As these areas grow, young plants may die quickly. Older plants can sometimes tolerate a low-level infection, causing lesions with reddish margins. If these spots appear low on stems though, the plants can be girdled and will die. Roots can also become infected, causing wilt symptoms including yellow leaves that don’t fall off the plant.
Grey Mould – 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. Also onions just before harvesting.
Mildew – (Powdery) mildew grows as a white powdery coating over the surfaces of leaves. Pea, bean, okra, cucumber, squash, muskmelon, and pumpkin are common host plants. Leaves around the base of the plant are first affected. This fungal disease is favored by warm weather and can be destructive in dry as well as hot seasons.
- End of life cycle
- Plant is weak
- Especially peas and beans
- Wet summer
All the fungal diseases are accelerated by weather conditions
Irish climate inherently conducive to fungal diseases; relatively little that can be done once a plant is diseased. So preventative measures are essential:
Start by planting healthy stock. … check seed descriptions for “mildew resistant”
Choose planting sites based on plant needs. … maintain plant distance
Remove affected material immediately
Avoid overhead watering. …
Water early in the day. …
Don’t crowd plants. …
Don’t work a wet garden. …
Ensure good airflow, keep tunnel doors open
But in the end there’s little that can be done (in an organic situation).
Potato Blight is prevented by bluestone (copper sulphate) solution. Seals leaves to prevent spores attaching to the plant.
Tomato blight – . .
Strictly blight spraying is not allowed by the International Organic System. But each country has its own overlays and it is accepted in Ireland. However, we know fluids travel up AND down the plant stems. So, we must ask whether we are happy with copper sulphate in our potatoes?
(and find they are not clear or helpful?) ☹
Also can try Horsetail Tea
Horsetail is a beautiful, highly invasive and incredibly resilient plant; a great survivor. With roots growing 10 feet and more into the earth and a history of survival stretching back over millions of years to the time of the dinosaurs, it is extremely difficult to erradicate so I never have living plants in my own garden and dispose of any roots with caution.
Horsetail is a powerful plant, rich in minerals, alkaloids and silica, used in some biodynamic preparations as well as extensively in herbal remedies. A natural fungicide, horsetail ‘tea’ is used to treat fungal problems including powdery mildew and black spot and makes a magnesium rich spray which can be applied directly to plants and as a soil feed. The spray helps to prevent damping off, rust, treats mildew on roses, make a root dip,is used to treat peach tree leaf curl and is an effective, purifying cleaner for greenhouses and cold frames.
Weed Control Actions
- Square foot gardening
- Dense planting
- Stale seed bed
- Flame thrower!!
- Allow 1 or 2 seed growths and then sow out
- Boiling water (kills weeds)
Pests: A pest is any animal or plant harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry.
- Plant out more than is needed
- Plant sacrificial crop
- Plant perimeter crop to deter (e.g radishes)
Companion Planting: Effects of Radishes on Squash Bugs
- Plant spicy leaves on perimeter
- Biological control (see Bacillus thuringiensis below)
- Parasitic wasps
BBC report on Parasitoid wasps
I note from FHF site that Borage is recommended as favourite plant for beneficials (spiders, damsel bugs, ground beetles, parasitoid wasps)
- Ecosystem problem? Move entire site for a few years! (drastic? Actually not necessarily if plots available!)
Slugs, snails, (no natural predators except thushes, geese, ducks). Remove, mulch, find in March). Good garden hygiene removes hiding places, use gravel paths, ensure nowhere overgrown. Use Neudorff organic slug pellets also stocked by Griffins, Dripsea
Note slugs eat toxic foliage (e.f rhubarb leaves) , and are themselves toxic
Caterpillars, cabbage white month mid summer. Consider biological control – bocillis thurengiensis . . .
Bacillus thuringiensis (Bt) is a natural occurring, soil-borne bacteria that has been used since the 1950s for natural insect control. It consists of a spore, which gives it persistence, and a protein crystal within the spore, which is toxic.
for control of larvae of wax moths and other moth species, larvae of mosquitoes, black flies, and other flies, many types of caterpillars, larvae of elm leaf beetle, larvae of elm leaf beetle
BUT . . . Not cheap see Fruithill farm below . . .
Alternatively consider Bionet netting, bit cheaper!!
Greenfly, blackfly, wooly aphids, aphids (love greenhouses, wet and warm conditions, really vicious little teeth, attract or buy ladybirds), they feed in clusters, usually on the undersides of leaves near the point where the leaf attaches to the stem, or on tender young shoots and buds. As they feed, they secrete a sticky fluid called honeydew. When enough aphids are feeding on the tree, this honeydew will begin dripping from the leaves. Solution – encourage ladybirds with wide variety of flowers.
Try Limnanthes douglasii (poached egg plants) around your raspberries and soft fruits: they will attract bees and so improve pollination and fruit production while also encouraging hoverflies which will feed on aphids.
Also consider natural insecticide spray, (deadly) nightshade leaves crushed with garlic, washing up liquid and cold water. (actually garlic alone works also IME)
NOTE: Blarney Castle Gardens has a Poisonous Plant Garden
Blarney Castle’s Poison Gardens are located behind the castle battlements. Though at a glance they may seem like any other botanical garden, warning signs with skull and crossbones and cages carefully constructed to contain the deadliest of the plants reveal this is no ordinary garden. . . Wolfsbane, Mandrake, Hellebore, Hemlock, Nightshade, and Ricinus communis, which produces castor oil and the lethal poison ricin.
white fly, root flies (carrot and cabbage),
cabbage fly – use collars around the plants
wire worms – trap with sacrificial potato plants
flea beetles, small bugs, tiny beetles attach to young brassicas/rocket and spicy leaves. Whole plant is riddled with holes!
also use nematodes – not cheap!! . .. small, usually microscopic, unsegmented roundworms with a narrow cylindrical body. They are not a pest and occur naturally in the soil. Buy from Fruithill farm
ants (find eggs at end of summer, white pearls – expose to birds), . . .
Pigeons – love brassicas
Coypu (in River Lee?)
NZ Flatworm – attack and eat earthworms. Kill on sight!!
Plants manufacture their own food under the influence of sunlight. It happens in the leaves of plants and is distributed to the rest of the plant via the stems. Note the stems separate transport (similar to the human arteries and veins) to facilitate transmission of water and oxygen (simplistically) up to the leaf structure and sugars down to the roots. When a plant is damaged the plant can be helped by cutting away damaged leaves and stems.
Carbon + Water = Sugars + Oxygen
CO + H2O = C12H22O11 + O
(note the chemical or molecular formula for sucrose is C12H22O11, which means each molecule of sugar contains 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.)
Credits: Many thanks to our tutor this term –
Selvi Lyilikci and the Cork Education Training Board (CETB)