Tips for tackling this month’s problems
As temperatures and humidity rise, foliage diseases start to appear in the patch, particularly on tomatoes and zucchinis. Generally, these are easy to manage if you get onto them early, but if you ignore them they can quickly take hold and set plants back. Get into the habit of walking around the patch every few days to remove anything that looks spotty or weird (normally found on older leaves) and toss it into your general rubbish bin. This keeps plants tidy and eliminates a major source of fungal spores that would otherwise spread. Avoid wetting foliage when watering as this splashes spores about and creates ideal conditions for foliage diseases to flourish.
If disease is getting away from you, despite your efforts to remove damaged material, consider applying an organic fungicide to the remaining healthy foliage to help contain outbreaks. Fungicides add a layer of protection to the leaf, preventing fungal spores from germinating. Copper hydroxide can be applied to tomatoes to assist in managing septoria leaf spot. Organic products based on potassium bicarbonate effectively shield zucchini foliage from powdery mildew and kill existing fungal spores as well. Reapply fungicides after rain and always follow directions on the product label.