April

With the cooling temperatures and more rain, hopefully even in the dry areas of the country, April sees the beginning of leaf fall for deciduous plants. This is an opportunity for fungal and bacterial diseases to enter your plants through the small scars left on the stems as the leaves fall off. These scars take a day or two before they heal sufficiently to keep these diseases out so regular spraying, especially of fruit trees, with copper will help protect your garden. Adding spraying oil with the copper will help control any scale insects, mites and white fly before they over winter. Spraying with copper will also help frost tender plants cope with any early cold snaps.
The other main thing to watch for is snails as they will be out and about more as the moisture levels rise. They are always hungry, so make sure you have spread plenty of snail bait around especially if you have planted any autumn seedlings.

Plant Health

Keep a look out for these pests and diseases in your garden.

Fruit

Verrucosis
Leaf Roller Caterpillar
Scale
Aphids
Vegetables:
Caterpillars
Aphids
Snails and Slugs

Roses & Ornamentals

Aphids
Caterpillars
White Fly
Mealy Bug
Snails and Slugs
Blackspot
Powdery Mildew
Rust