1.Blossom End Rot
This disorder appears as dark patches on the blossom end of plants such as peppers, tomatoes, aubergines etc. The problem is caused by a calcium deficiency in the affected plant or plants. Calcium is not typically lacking in soil so the most likely issue is that it is not reaching the parts of the plant furthest from the roots due to not enough water. Plants grown within limited root space such as pots or growing bags are at a greater risk since the water either from rain or you is not consistent enough leading to a local calcium deficiency. Keeping the plant moist throughout the season is the best way to prevent this problem.
2.Chocolate Spot
This disease causes dark brown spots to appear on the foliage and stems of plants, notably broad beans. This effectively reduces the vigour of the plant or kills it entirely. The fungus that is responsible for it thrives in damp areas with low air circulation. The best way to avoid it is to make sure you are growing plants in well drained soil and that you give your crops the correct spacing.
3.Botrytis
This is another fungus that negatively affects plants. It causes decay of the soft tissues of fruit such as raspberries, strawberries, grapes etc. It is a fuzzy grey-brown looking mould that commonly attacks plants grown under glass cover where conditions will be more humid. If you are growing plants under cover, make sure to remove dead plant material and allow for a small amount of ventilation. Some modular trays are designed to have small gaps at certain intervals where the cover meets the actual tray. This promotes a small amount of air flow which will decrease the chance of this mould developing.
4.Damping Off
This particular disease causing your seedlings to suddenly collapse and die. Like the previous disease, it is caused by fungi. To reduce the risk, plant seeds thinly and keep good ventilation. As mentioned in one of my other articles, use clean pots and containers and mains water.
5.Powdery Mildew
This disease causes powdery white layers on leaves and stems and is fairly frequent. They're actually a collection of related fungi. When the weather is dry, it's even worse. Among the many common culinary and ornamental garden plants impacted are apples, gooseberries, grapes, crucifers, courgettes, cucumbers, peas, and even some grasses. Powdery mildew fungus are also damaging to grain crops. One way to prevent the development of this common problem is to mix a solution of baking soda and dish soap with water in a spray bottle. This will act as a preventative so that you don't have to deal with the mildew to begin with.
That was five common diseases and disorders that you may or probably have encountered at some point when gardening. I would like to remind you to check out my channel on Youtube where I post gardening related videos. My Youtube Channel