Is there an organic control for caterpillars on cabbages?

Yes, it is possible to organically control caterpillars.

If no attack has yet started, cover the crop with an agricultural fleece, the fine mesh will exclude the egg-laying butterflies.

If there are already caterpillars on the crop, spray with the biological control bacillus thuringiensis, this is a special bacterium species that attacks and kills caterpillars.

It can be obtained biological control specialists.

When is the best time to sow spring cabbage seed?

Spring cabbage seed should be sown in early July (circa Week 26) in Scotland and the north of England and about a fortnight later in the South.

How do you stop cabbage root fly attacks?

Try covering your plants immediately after planting out with an ‘agricultural fleece’

Plant out in a different bed each year to ensure you are not affected by over wintering fly pupae in the soil.

I have whitefly on my sprout leaves, is this the same type that attacks indoor plants, and if not, how do I control them.

The species of whitefly on brassicas is a much hardier strain than that which lives under glass, and will survive the hardest of winters, and it is just as difficult to control.

Fortunately, it doesn't do as much damage as glasshouse whitefly.

To control them, apply two or three sprays of insecticide when you first see them.

It is advisable to alternate varieties of pesticides to cater for the possibility of the aphid developing an immunity to one variety.

I have come across some small white maggots eating the roots of my cabbages, how do I get rid of them?

The small white maggots are the larvae of the 'Cabbage root fly' and they live in the soil and eat the roots of cabbages and other brassicas.

Infested plants wilt, especially in dry weather, and young plants may be killed.

The adult flies are active in April and May when they lay their eggs on or near plant stems at soil level.

Three generations of adults develop during the summer and attacks may persist until mid-September.

This pest is now resistant to many of the insecticides available to the amateur, so it is best to alternate between different pesticides at each treatment, thus reducing the chances of non resistance.

Jeyes fluid although a disinfectant can be applied as a soil drench prior to planting,

It is thought that the fly is deterred by the smell so it moves on and lays its eggs elsewhere.

When I disturb the leaves of my cabbage and sprouts masses of white flies take to the air, do they harm plants and how do I get rid of them?

This pest of cabbages and other brassicas is often only noticed when plants are disturbed, and the small adult whiteflies are seen to fly off the leaves.

Whiteflies are often seen during winter, when most other insects are dormant.

The young whitefly scales feed on the undersides of leaves, causing foliage dis­coloration and checking plant growth when present in large numbers.

To control them, apply two or three sprays of a suitable insecticide when you first see them, but is only necessary if damage is severe.

My spring cabbage plants get badly damaged by birds each year, can you suggest how I might deter the birds?

The most effective way of deterring birds is to cover your plants with netting on a temporary framework.

An alternative, is to use humming tape around the plants.

The leaves on several of my brassicas, mainly sprout and cabbages have developed rings of raised white spots, can you help please?

The disease you describe could be white blister.

It can attack most plants in the cabbage family, including honesty.

The best control would be to remove the worst leaves and any fallen ones, then spray with a fungicide.

After cropping, dig out and burn all plant residues and follow a crop rotation to keep new seedlings and plants away from older ones.