Preventing Plant Diseases
Keep a close eye on your garden and take immediate action at the first sign of disease. To prevent problems, choose disease-resistant varieties of plants whenever possible.
The correct way to water plants
To discourage fungal diseases such as powdery mildew, water the plants in your garden early in the day so that the foliage is completely dry by nightfall. T he best time to water them is in the early morning.
Avoid watering during the heat of the day. Plants can be scorched when the water droplets on their leaves magnify the sun's rays.
Tips for healthy plants
Keep your soil healthy and nourished by adding compost and other organic nutrients during the year. Provide plants with sufficient water to keep them strong, feeding them as needed with fertilizers. Keep your garden clean; regularly pick up leaves, fruits, and berries from the ground.
Enlist the sun to kill soil-borne pests
If you are struggling with soil-borne, disease-causing, or tenacious pests such as nematodes, try solarizing your soil. This raises soil temperature high enough to eradicate diseases and pests. Because it also kills beneficial insects and soil organisms, solarization should only be used as a last resort.
To solarize soil, remove all plants and weeds, cultivate the soil, rake it smooth, and thoroughly water it Dig a trench 1 5 cm (6 in.) deep around the perimeter of the bed, and stretch a sheet of medium-weight plastic over the bed, pressing it down so that it touches the soil.
Tuck the plastic into the trench, fill it with soil, and leave the plastic in place for two months. When you remove it, add compost to help restore the beneficial micro-organisms to the soil.
Treat powdery mildew
Powdery mildew looks like a white or grey coating on foliage. It spreads quickly, causes leaves to shrivel, and deforms new growth.
The fungus affects many vegetables and flowering plants, and is most troublesome in autumn. Wash the leaves weekly to keep the spores from germinating or spreading. Then spray on these ingredients:
• 1 teaspoon light vegetable oil
• 10 drops tea tree essential oil
• 1 teaspoon baking soda
• 5 litres (1 gallon) water
Mix the oils together and add to the baking soda and water. Shake well, and spray liberally on to affected plants once a week
Prevent blossom end rot
Tomatoes, peppers, cucumbers, squashes, and melons can suffer from blossom end rot, a disease that causes a dark sunken area at the blossom end; the area can grow to cover half the fruit It's caused by a calcium deficiency or by uneven watering.
To prevent blossom end rot, add composted manure or bone meal when preparing garden beds prior to planting; doing so supplies calcium. Ensure that plants get approximately 25 mm (1 in.) of water per week from either rain or irrigation. Mulch plants to keep the soil moist
Prevent damping-off
Damping-off is caused by soil-born fungi that make seedling stems rot and collapse at the soil level. The fungi can also decay seeds before they sprout.
To prevent damping-off, avoid planting seeds too deep. Keep the soil moist but not soggy. Ensure your plants have good air circulation if you're planting them indoors. Planting in a sterilized planting mix eliminates the possibility of fungi in the soil.
If you are re-using containers that have been previously used to grow plants, clean them thoroughly; this destroys damping-off fungi. Wash them in hot soapy water, rinse well, and let them dry in the sun for a couple of days.
Prevent black spot
Black spot is a common fungal disease that affects many roses. The disease appears as round black spots surrounded by yellow rings on the leaves; it can seriously weaken plants.
To prevent black spot avoid overhead watering, and apply fresh mulch each spring. To treat it, remove and dispose of infected leaves and spray with the following ingredients:
• 1 tablespoon baking soda
• 1 teaspoon natural liquid dish washing
• soap
• 5 litres (1 gallon) lukewarm water
Mix the ingredients together in a pump-type garden sprayer and spray on your plants once a week
Epsom salts boost
To improve calcium uptake and prevent diseases such as blossom end rot, add two tablespoons of Epsom salts to the hole in which you are planting tomatoes, peppers, cucumbers, squashes, or melons.
