Cabbage Integrated Pest Management : An Ecological Guide.

Major Agronomic PracticesHowever, when the intercrop is taller than cabbage, or grown very close to the cabbage plants, it maycause yield reduction due to competition for light, space and nutrients. Other disadvantages includemore difficult harvesting operations due to different ripening times of the crops, and the planning of croprotation schedule is more complicated. Intercropping is usually a bit more labor intensive.How to try intercropping in your field:Take a small portion of your field, for example a few square meters and plant both cabbage andtomato, a few rows of each. The remaining part of the field is planted with cabbage. Monitor a fewplants weekly for the numbers of pest insectsand the incidence of diseases. Check ifthere is less infestation of diamondbackmoth (Plutella xylostella) and other insectpests or diseases in the intercropped areaas compared to the portion of the fieldin which only cabbage is grown. Trydifferent crops for intercropping, forexample cabbage-onion, tomatoonion.3.10.2 Trap cropsA trap crop is a crop other than cabbage that attracts insect pests so that these pests will not harm thecabbages. Usually, trap crops are also members of the cruciferous family because they have to attractthe same insects that will attack cabbage. Some people find this is a disadvantage of planting trap cropsbecause pests are attracted to the field…..!The trap crop should be sown thickly all around the area where crucifers will be grown, at least 10 daysbefore the cabbage is transplanted. The idea is that the trap crop is established in the field earlier thanthe cabbage so that pests will attack the trap crop first. Then the infested trap crop can be destroyed butit can also be treated with pesticides, or left in the field. The advantage of leaving the trap crop may bethat the infested trap crop attracts natural enemies that will be present when the cabbage plants will beattacked by pests. When pesticides are used on the trap crop, there is a risk that (especially) diamondbackmoth builds up resistance against pesticides faster than without treatment.Several studies report that (Indian) mustard is an effective trap crop because it reduces numbers of pestinsects, and in some cases, improves yield of the main crop.For example, field studies in India showed that diamondbackmoth (Plutella xylostella), cabbage heart caterpillar(Crocidolomia binotalis), and aphids (Brevicorynebrassicae) preferred mustard to cabbage when thechoice was available. The ideal crop combinationin this study was 9 rows of cabbage followedby 1 paired row of mustard. In one of theserows mustard should be sown15 days before cabbage, andin the other row, mustardshould be sown 25 days aftercabbage (Srinivasan, 1991).47 Cabbage Ecological Guide - 2000