IPM-Brassica

Integrated Pest Management (IPM) helps growers select the best tool to manage pests.

Moth Diamondback Moth (DBM), Plutella xylostella, is a major pest of Brassica vegetable growing in Australia and it has the ability to rapidly become resistant to insecticides.

The National Diamondback Moth Project Team was established to research and communicate an integrated approach to managing this pest. During the six years of project work the team has focused on limiting DBM’s development of insecticidal resistance and facilitating the implementation of effective alternatives to insecticide-based control.

Significant tools have been developed to assist growers and consultants to better manage DBM.

Clubroot, caused by the organism Plasmodiophora brassicae, affects crucifer plants including broccoli, cauliflower, Chinese cabbage, Brussels sprouts, bok choy, cabbage, Swedes, radish and turnips. It can also persist in cruciferous weeds (eg wild turnip and wild radish).

Symptoms include wilting of plants during warm weather and the formation of enlarged galls on the roots. The galls prevent the uptake of water and nutrients, reducing the potential yield of the crop.

Integrated management of clubroot aims to achieve a soil environment that ensures the spore population remains below the threshold required for the disease. This is best achieved using a combination of management techniques.

1. Improve hygiene - Spores can be transported by anything carrying soil or water including machinery, shared/contract labour and equipment, boots, livestock, pallets, transplants and dams receiving run-off from affected paddocks.
   
   
2. Modify the soil Environmental factors can be managed to create soil conditions that restrict disease development.
   • Clubroot is less virulent in high pH soil. Apply lime to maintain a soil pH of 7.0 – 7.5.
   • Calcium and boron affect the growth and reproduction of clubroot and application should occur at transplanting and during the first four weeks of the life of the crop, to protect the vulnerable roots.
   • Clubroot requires free water to assist with movement through the soil. Improve drainage by using raised beds for cropping or laser grading low lying areas. Avoid overwatering.
   
   
3. Rotate crops Increase the duration between successive brassica crops to allow natural decay of the spores. Rotate with non-brassica crops and maintain crops free of cruciferous weeds. Chinese cabbage is most susceptible to clubroot, followed by cauliflower, cabbage and broccoli. However, some cultivars within a species are tolerant
   
   
4. Use fungicides wisely Application of fungicide may also be necessary in paddocks with previously high levels of disease. It is important to evenly distribute fungicides around the transplant root zone. This is best achieved by incorporating the fungicide into the transplant row at planting.
   
   
5. Know the disease risk Effective on farm application of integrated management techniques will require some estimation of likely disease risk and will depend on:

   • Sowing time
   • Soil type
   • Drainage
   • soil pH,
   • crop - including variety
   • cruciferous weed hosts