Excellent weed control; cowpeas cycle nitrogen and phosphorus well
Fertility Management
As a legume, cowpea fixes its own nitrogen, and does not need nitrogen fertilizer. In fact, some of the vigorous, vining, varieties cowpeas are excellent nitrogen producers as a cover crop. Seed should be innoculated with the appropriate Rhizobium species optimum nitrogen fixation, but nodules will generally form on cowpeas. Potassium and phosphorus needs have not been studied for cowpea in Missouri. Using the amounts recommended from tests for soybeans would be appropriate. Soil pH should be 6.0 higher.
Pest Management
Weed Control
Options are less extensive than for soybeans, but several products are available. Labeled herbicides* are Authority, Dual, Poast, Pursuit, and sodium chlorate. Pursuit provides some broadleaf control, while all the products control grass weeds. However, row crop cultivation may be necessary with cowpeas, depending on weed pressure, soil conditions, and rainfall. Preplant tillage can greatly help reduce early weed pressure, or cover crops such as can potentially be used for weed control.
Cowpea bruchid
Diseases and Insects
These have not been a problem in Missouri field trials. However, number of diseases and pests are reported in other locations, active breeding has taken place for resistant varieties. In southeastern production areas, the major insect pest is cowpea curculio, and the major disease is root-knot, a severe root disease induced by root-knot nematodes (Meloidogyne spp.). Cowpeas attract an unusual number of pollinating insects when flowering.
Possible diseases are fusarium wilt, bacterial canker, southern blight, cowpea mosaic virus (and several other less prominent viruses), cercospora leaf spot, rust and powdery mildew. The following fungicides* are registered for cowpeas—Maxim, Maxim-XL, Mefenoxam, Metalaxyl, Mycostop, Ridomil-Gold andThiram.
Possilbe insects are Mexican bean beetle, bean leaf beetles, cowpea curculio, aphids, green stink bug, lesser cornstalk borer and weevils (when in storage). The following insecticides* are registered for cowpeas—Adios, Azadirachtin, Bacillus thuringiensis, Capture, Di-Syston, Gaucho, Insecticidal soap, Lorsban, Methaldehyde, Methomyl, Pyrellin, Pyrethrin, Sevin, Success, Telone, and Trilogy.
*Pesticides mentioned as being labeled in this publication are based on reference lists published in the Thomson Publications “Quick Guide” on crop pesticides, 2002 edition. These lists are believed to be accurate, but given the changing nature of herbicide registrations, labels and relevant government regulations should be checked before applying any pesticide.
Cowpeas that had been harvested but left in fields prior to storage
Harvest and Storage
For the cowpea seed market, quality of seed is important, so care in harvest and post-harvest handling may be important to avoid cracked or split seed. Cowpea grown as a dried pea product can be direct combined using a platform head or a row crop head. Adjustments to combine settings, and possibly screen/sieve sizes, should be made for the cowpea seed. It is slightly larger than soybeans and kidney shaped. The grain can be stored short term at around 12% moisture or less, with 8 to 9% recommended for long term storage. Since the pods are relatively long, some will touch the ground or be close to it, making it important to run the grain table close to the gound. Some buyers will want the seed cleaned and bagged, while others will take the grain in bulk form and clean it themselves. For some markets, the cowpeas must be harvested at a higher moisture, such as 18%, and trucked directly from the field to the processor.
