Weed management in mungbeans
Mungbean seed lots containing weed seeds can be difficult to sell, and can incur substantial discounts. Contamination of the sample with either grain sorghum seed or thorn apple is of particular concern, as they are extremely difficult to remove by grading. These two weeds should be removed from the crop either with herbicides, or by hand roguing.
Contamination of the sample with wheat and barley seed can also cause problems as they are difficult to remove during grading, and can result in heavy discounts when being traded in the sprouting market. Contamination with cereals is most likely to occur in double-crop situations where mungbeans follow wheat or barley. Delaying planting until a kill can be achieved on volunteer cereals can often rectify the problem. Otherwise a grass herbicide will be required in-crop. Read product labels for details of application rates and withholding periods.
Trifluralin and pendimethalin can sometimes reduce seedling vigour and affect establishment in mungbeans. Trifluralin should be applied 2–3 weeks prior to planting to minimise the likelihood of crop damage. Avoid using high rates if applied just prior to planting. Trifluralin requires incorporation and is not suitable for zero or reduced-till situations. Spinnaker is a residual herbicide with extended plant back periods. Check with your agronomist before use.
Growers using acifluorfen should take particular note of label recommendations and discuss with an agronomist prior to use since nozzle selection, water volumes, weed growth stage and choice of surfactant can have a significant impact on the results obtained. Avoid applying acifluorfen during the heat of the day as burning of the foliage may occur. To minimise burning, apply very early morning, late afternoon or at night. See the label for registered use pattern in mungbeans.
Mungbeans offer an excellent opportunity to control difficult-to-manage grass weeds with Group A herbicides registered for use in mungbeans.
When using Group A herbicides, make sure coverage is adequate, use adjuvants to improve uptake and only apply to actively-growing, small plants.
Broadleaf weed control options are very limited in mungbeans, and growers should plan a weed strategy with their agronomist prior to planting.
The range of weeds encountered in Central Queensland often pose major problems and require a planned approach, using a combination of the available herbicides. Because of specific use characteristics of the limited range of herbicides available, it is best to plan a weed management strategy with your consultant prior to planting.