Garden Fungi
While the summer can bring a bumper crop of garden harvests, it can also bring a plethora of potential fungi. Blight, powdery mildew, and blackspot are common diseases that ail garden crops. These diseases all have a number of synthetic and non-synthetic solutions, many of which the Essex County Co-Op sells!
Blight is a fungal disease that spreads very rapidly, through spores that are blown in the wind from one area to another. There are two types of blight, early blight and late blight. Early blight appears as dark, sunken lesions just above the soil, while late blight appears as brown and black lesions on the stalk and leaf stems. Late blight is what caused the Irish potato famine in the 1840s, as it destroys crops within a matter of weeks. Blight only spreads under warm, humid conditions, and generally spore production does not begin until there is a period of two or more consecutive days above 50ᵒF and humidity above 90% for at least eleven hours. Brown patches on the leaves are the first sign of blight, and once blight has started to damage a plant, you must act quickly to knock it down.
With late blight, you should dispose of the infected plant in a manner that the disease cannot spread to other plants. Dig up any infected root systems to prevent it to spreading to crops next year, and be sure not to compost any of these things, as it will continue to spread.
Late blight cannot be cured once it has infected a plant, however, there are some steps that can be taken to prevent severe damage. A common technique is to apply fungicide regularly, and that often involves spraying plants with a
copper-based fungicide, such as Bonide Liquid Copper Fungicide, or a synthetic fungicide like Bonide Fung-Onil Liquid Fungicide. While this method is effective, the fungicide is easily washed off by rain, causing the fungicide to need frequent reapplication. Growing under covers can also prevent the fungus from spreading, as the airborne spores cannot land on plants. Good hygiene, however, is the most effective way to ensure that blight does not spread year over year.
If you have early blight, remove the lower affected leaves and branches, and plant in a different location next year. When watering the plants, do not water the leaves, especially in the evening as moisture on the leaves leaves it susceptible to blight. If you suspect you have late blight, however, you must immediately remove and destroy the plant to prevent disease from spreading. It is imperative you plant in another location next year, so as to prevent the same thing from occurring.
Similarly to blight, powdery mildew is a fungus that spreads through spores that have blown through the air. This mildew affects a wide variety of plants and is easily identifiable as it appears as light grey or white powdery spots. Powdery mildew usually appears on the topside of the leaves; however, it can also be found underneath leaves, on stems, on fruit, or on flowers. The spots spread, with new growth being most susceptible, and deprive the plant of water and nutrients, thus damaging and ultimately killing the plant if it is left untreated. Powdery mildew thrives in warm, dry climates that have periods of humidity. An example of this periodic humidity would be warm days and cool nights, which causes moisture to linger close to the ground where growing plants are. Lack of sunlight and poor air circulation also contribute to powdery mildew.
It is easier to prevent powdery mildew than it is to rid a
plant of it, so there are a few steps that should be taken to
ensure an
unaffected crop. You should thin out existing plants, and maintain adequate
space between plants and
fences or walls, both of which allow for good air circulation. Additionally,
you should plant plants in areas in which they will require the correct number
of sunlight hours that they require, and maintain healthy plants by removing
dead or diseased foliage. Regularly applying a fungicide with sulfur as the
active ingredient can help prevent powdery mildew from breeding on your plant
and should it appear, this can be used as a curative product. An example of a
sulfur fungicide would be Bonide Sulfur Plant Fungicide, which is a powder that
is dusted on the plant. Sulfur fungicides also come as a wettable powder, which
is a powder that is mixed with water and then sprayed on the plant. While
sulfur fungicide is considered an organic solution, some might prefer baking
soda solution where two parts baking soda is mixed with one part liquid soap
and sprayed liberally on the plant.
Blackspot is a condition that predominantly affects the fruit of tomato plants, however it can also affect melons, cucumbers, and peppers. This disease appears as brownish, blackish spots on the blossom (bottom) end of the tomato. Secondary organisms invade the vulnerable spots, causing decay of the fruit. Blackspot is caused by a calcium deficiency in the developing fruit. Wide fluctuations in soil temperature, and therefore soil moisture levels, which are common in our area, impair the calcium uptake by the root system of the plant. Excessive nitrogen fertilization can also contribute to blackspot.
Reducing blackspot is easier than reducing blight or powdery mildew. To reduce blackspot, water tomatoes in dry weather to reduce fluctuations in soil moisture. Additionally, tomato plants should be mulched around to conserve soil moisture.
No matter what ails your garden, stop by the Essex County Co-Op for expert advice on how to address the issues you face!