In depth article on aphids
Look for colonies of greenfly on the soft shoot tips of plants or on leaves. They suck sap and excrete sticky honeydew, encouraging the growth of black sooty moulds.
Remedy: Use your finger and thumb to squash aphid colonies, spray with pyrethrum, plant or fish oils or use the biological control aphidius or aphidoletes in the greenhouse.
There are many types of aphids and they can be a pest across many crops. Natural predators are a good means of tackling them.
Rhubarb is an attractive hardy perennial with large leaves and pink, red or greenish leaf stalks that are used as a dessert, often in pies and crumbles. Stems are usually picked in spring, but plants can be covered with pots to produce an early crop of blanched stalks in late winter. The flavour of stems varieties in sweetness depending on the age of the stems.
Rhubarb needs an open, sunny site with moist, but free-draining soil as it hates being waterlogged in winter. Avoid frost pockets as stems are susceptible to frost.