BLISTERED LEAVES - Small white grubs can burrow into the leaves, causing tunnels which turn into blisters. These attacks can occur from May onwards and the effects are most serious on small, young plants. Growth is stunned as the leaves turn brown. Pick off & destroy damaged leaves, and treat with malathion at the first sign of attack. No prevention is possible.
HEART ROT - The leaves wilt in the summer, and the tops of the roots develop brown sunken patches. A cut root reveals blackened areas within the flesh. The cause is a boron deficiency in the soil. Spray with a trace element periodically, but be careful not to overdo it, as this will cause more harm than good.
BLACK LEG - A serious disease that affects young seedlings. They turn black, then shrivel up and die.. The normal causes are when the seeds are sown too thickly, and not thinned out, or compacted soil becomes too waterlogged. Remove the affected plants and water the remainder with Cheshunt Compound.
BOLTING - Plants can sometimes run to seed before the roots have developed. Dry soil or the addition of organic matter just before planting is the usual cause, but it will also occur if you wait too long before thinning out.
FANGING - Forked roots (Fanged) are normally caused by adding fresh organic matter just before planting. Also may caused by planting in stony soil, or land not properly cultivated. Add well rotted compost in the autumn the year before, to allow it to rot down further, then sow seeds as normal the following year.
SPECKLED LEAVES - Yellow patches develop between the veins, and the leaves turn yellow/brown and roll inward. Manganese deficiency is the main cause. Spray with a trace element compound, and do not over lime the soil before sowing.
LEAF SPOT - Brown spots appear on the leaves. The leaves may look bad, but it's unlikely the yield of the crop will be reduced. Practice crop rotation, and apply a balanced fertilizer before sowing seeds.