Good establishment techniques are important for brassicas, more so than for pasture, because of their low sowing rates.
Plant population has a large influence on crop yield, so seed treatments such as AGRICOTE Brassica are important to the success of crops.
Brassicas can benefit from following another crop, e.g. short term ryegrass or cereal. This gives the opportunity to fix underlying problems with the paddock (poor drainage, fertility etc) and provides a better seed bed for brassicas. Longer term, new pasture sown post brassicas will benefit from fewer pests and weeds, especially grass weeds like browntop. It can also be a good idea to apply insecticide when spraying out old pasture.
When sowing into cultivated paddocks, a fine, firm, moist, weed-free seedbed is essential. Bury previous crop or pasture residues to reduce the risk of pests and diseases. Seed should be sown shallow (no more than 10 mm) to ensure good, even establishment of the crop. A level seedbed with good consolidation can greatly help achieve an even sowing depth.
An alternative where cultivation is not appropriate. When direct-drilling brassica crops, a thorough herbicide application is required to minimise weed competition, especially in the seedling stage. Nitrogen fertiliser requirements are likely higher as N is tied up in decaying vegetation. Also, insecticides should be used to minimise insect pressure, as the dead vegetation is an ideal haven for brassica insect pests, particularly springtails and slugs. It is important to remove as much turf as possible before sowing through hard grazing.
Insect damage can be catastrophic to seedling brassicas, and seed treatment (e.g. AGRICOTE Brassica) is always recommended. Treating seed will reduce the risk of crop damage and failure during establishment.
Weeds must be controlled from the outset as they compete strongly with brassica seedlings. Pre-emergent herbicides can be incorporated into the seedbed before sowing.
Monitoring insects and diseases
Weeds can also be a real problem in second year crops, e.g. fathen, red shank and nodding thistle in kale. These are best controlled in the first year crop by stopping their seeding.
Pests can cause serious damage to brassica crops, during establishment and through the life of the crop. Monitor crops daily for the first 14 days after emergence, and then weekly. Information on pest and disease identification is given on pages 151 to 166. There should be a gap of 5 years between some brassica crops.