A number of fungi and bacteria attack stems, and fleshy parts such bulbs, tubers, and fruit of plants, causing rots which may be wet or dry. These pathogens frequently enter through damaged tissue, and are mostly prevalent in wet, humid conditions.

Most common among the bacterial spots are – tomato speck, & angular spot of beans and cucurbits, plus halo leaf spot of geraniums.

A number of fungal diseases exist in the soil and attack the roots of plants. Symptoms vary between the particular fungi and each crop. Affected plants wilt and lack thrift, leaves yellow and fall, and eventually the plant collapses and dies.

Aphids are one of the most common pests in the garden, which attack a wide range of plants. There are a number of different species of varying colour (black, brown, grey, green, mealy, white) each of which attack specific hosts at different times of the year.

These diseases are grouped together because they all produce visible moulds, mildews or rusts, which are the fruiting bodies of the attacking fungus. The fungal pathogens causing mildews and rusts are spread mainly by wind and rain, but can also be spread by insects or are seed-borne.