common garden diseases
Before even looking for applications to treat plant diseases, try to prevent initial infection by being prudent about proper garden hygiene. Constant and thorough cultivation of the soil will greatly reduce the risks of disease occurrence. Choosing vigorous, hardy plants will also protect against a variety of diseases. Many plant growers subscribe to virus-free certification schemes. So when you meet them, it’s a great idea to only use certified specimens.
Most of the chemicals that deal with diseases are only preventatives. So when the disease is identified, be absolutely sure to cut back affected areas of the plant or uproot entire plants if the disease is out of control. Never fail to thoroughly burn all the resulting debris.
Keep plants in the prime of health and feed them well. This will make them more resistant to disease attacks. But, if disease does occur, here is an alphabetical guide to identifying diseases and the correct methods of treatment.
Disease: black spot
attacks: roses
Recognizable symptoms: dark blotchy spots on leaves that will later appear anemic and
ultimately fall
Treatment: spray often with captan, zineb or benomyl
disease: blight
Attacks: potatoes and tomatoes
Recognizable symptoms: leaves are blotchy, brown and rotten; gray patches
observable in tubers
Treatment: spray every 14 days with liquid copper, zineb, maneb or Bordeaux broth
Disease: botrytis (gray mold)
Attacks: Varied plants but has a predilection for strawberries and tomatoes.
Recognizable symptoms: rotten leaves, covered with a velvety mildew
Treatment: Address this problem as soon as you detect it; a general purpose garden fungicide is
ideal
Disease: cane spot
Attacks: blackberries, blackberries and raspberries
Recognizable symptoms: regular round dark spots appear on the stems, then turn white and split open.
Treatment: dilute water with 5% lime sulfur and spray when the first buds appear, reduce the dilution to 2.5% and spray when the flowers appear
Disease: chocolate stain
Attacks: beans
Recognizable symptoms: brown spots on the leaves during the summer and also after the first winter frosts.
Treatment: Spray immature leaves with a copper-based fungicide
Disease: club root
Attacks: mainly brassicas, but also wallflowers and broths
Recognizable symptoms: wilted foliage and distorted, swollen roots
Treatment: Lime the surrounding soil liberally; dust holes with 4% calomel before planting
disease: damping
Attacks: variety of herbaceous plants but highlights lettuce
Recognizable symptoms: seedlings wither, rot and eventually collapse
Treatment: diluted Cheshunt compound, zineb, or captan
Disease: peach leaf curl
Attacks: almonds, nectarines and peaches, even non-fruitful ornamental vines
Recognizable symptoms: red blisters on the foliage, turning white over time, then brown; the leaves finally fall
Treatment: in the middle of winter, spray with Bordeaux mixture or lime-sulfur
Disease: petal blight
It attacks: dahlias and anemones, but saves the worst for chrysanthemums.
Recognizable symptoms: petals darken in wet periods
Treatment: use zineb immediately before flower buds open
disease: powdery mildew
Attacks: an absolute multitude of plant species
Recognizable symptoms: a pale, powdery coating on leaves and shoots.
Treatment: spray frequently with dinocap or benomyl
disease: rust
Attack: numerous flowers and vegetables
Recognizable symptoms: orange spores on foliage and stems
Treatment: nebulize often with zineb (once every fortnight or once a month, depending on the severity of the disease)
disease: scab
Attacks: apples and pears
Recognizable symptoms: brown scabs on the fruit
Treatment: captan, benomyl and lime-sulfide are all effective
Disease: Fire Tulips
Attacks: Tulips
Recognizable symptoms: the shoots rot and the bulbs are covered with dense black spores.
Treatment: Just before planting, spray bulbs and soil with Quintozene.
Keep in mind that most diseases cannot be eradicated without severe intervention by cutting the affected areas, but equally that diseases can be controlled with correct but not too aggressive treatment with organic products. There is a solution to virtually every problem, which is why the most important attribute to have is an eagle eye. Detect and identify problems early, and you won’t go far wrong.