Need for persistent weed control in increased area of winter beans

The area of winter beans has increased substantially this autumn and not just because of the difficulties of drilling oilseed rape or second wheats. The cash flow benefits of growing a lower cost crop plus good yields achieved this year means the popularity of drilling winter beans has greatly increased, according to Mark Hemmant, Eastern Region Technical Manager for AgroVista.

"The winter bean crop yielded well this year and, with financial pressures increasing on farm, many growers have shifted to growing beans due to lower input costs and the benefits of added free nitrogen into next years crop. But with this increased area there will be new or lapsed winter bean growers, who may not have grown this crop for a number of years and will not be fully briefed on the weed control options now available. The herbicide sector in beans has changed substantially over the past few years with losses of many active ingredients. This year will be the first without simazine which was a useful and very cost-effective option. In addition, there is also only a limited amount of trifluralin in the market for bean growers to use. So what options do we have?" says Mark.

"Overall, the choice of actives with full label recommendations for use on winter beans is limited. Clomazone is one option: another is imazamox plus pendimethalin in combination (Nirvana). Pendimethalin (Stomp 400SC) and prosulfocarb have SOLAs. For grass-weed control you have propyzamide and carbetamide. Post-em options are even more limited to bentazone (Basagran SG) in the spring. Of these options Nirvana is the one that stands out with excellent broad-leaved weed control including brassica species and

excellent persistence which is needed in winter beans."

Mark considers that Nirvana gives very good broad-leaved weed control, with particular strengths on brassica weeds including Charlock and Volunteer oilseed rape. "There will be a lot of volunteer rape in crops this year as there is a lot in the rotation and harvest wasn’t easy. Not many other herbicides will control these weeds as effectively as Nirvana."

"Nirvana is recommended pre-emergence in all varieties of winter beans and, with limited post-emergence options, growers must be aiming to get as much as they can from the pre- emergence treatment. Because winter beans are very uncompetitive, particularly in the autumn and winter, you need a product that has a good weed spectrum, gives high levels of control plus long persistence well into the autumn and winter period. The most residual-acting active ingredient with good weed spectrum for use in beans is pendimethalin, one of the two actives in Nirvana. Trials and commercial use have demonstrated its superior residual activity. It has good activity on important polygonum weeds such as Fat-hen and Black-bindweed and delivers this through its long lasting residual activity. Pendimethalin also has some important added grass-weed activity on Black-grass and Annual Meadow-grass. The imazamox in Nirvana adds additional weeds such as Charlock, Black-bindweed, Volunteer Oilseed rape and Cleavers to the overall package," explains Mark Hemmant.

"The excellent results from Nirvana in beans can be further enhanced through the use of the specialist pre-emergence adjuvant system, Grounded. Grounded works by reducing spray drift, improving spray deposition pattern and increasing adsorption onto soil particles, which keeps the herbicide where it should be. This results in better performance and improved reliability of residual herbicides such as Nirvana. In the autumn Grounded dose rate is 0.2 l/ha."

BASF’s Steve Dennis advises that for the longest persistence and optimum efficacy under high weed pressure the full rate of Nirvana, 4.5 l/ha, should be used. "For general weed control in low to moderate weed populations, Nirvana can be applied between 3-4 l/ha. It can also be used at 2.5-3 l/ha in conjunction with suitable tank-mix partners such as clomazone for enhanced control of certain problem weeds such as Cleavers or Shepherd’s-purse. But it is important to note that this lower rate may weaken Nirvana’s persistence and hence its activity on other key weeds such as polygonum species that germinate later."

Background Notes - Nirvana contains 16.7 g/l of imazamox and 250 g/l of pendimethalin, formulated as an emulsifiable concentrate, packed in 10 litre containers. It is recommended in winter field beans as well as combining peas, vining peas and spring field beans for the control of broad-leaved weeds including Black-bindweed, Charlock, Common chickweed, Common Field Speedwell, Common Fumitory, Common Poppy, Fat-hen, Henbit Dead-nettle, Ivy-leaved Speedwell, Knotgrass, Orache, Red Dead-nettle, Redshank and Scarlet Pimpernel. Nirvana is applied pre-emergence of the crop at a dose rate between 2.5 – 4.5 l/ha in 200 – 300 litres of water per hectare, with the dose rate depending on the crop, weed pressure, weed spectrum and length of persistence required.

For further comment and information please contact:Jonathan Ball, BASF on 0161 488 5785 or mobile 0771 7782768