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Read all the latest news from the agronomy services industry.

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Weed Control in Maize

Weed Control in Maize

Published: Saturday, May 12, 2018
Category: Technical News

Application timing, weed size and water volumes are the keys to effective weed control

A recent move to Pearce Seeds has led to new agronomic challenges for Adam North (Pearce Seeds Agronomist) following his previous role as Assistant Farm Manager on a 3,200 ha arable estate in Cambridgeshire.

           “I joined the company just over a year ago now covering a large territory from Wincanton across to Minehead and extending north of Shepton Mallet down to the A303. Beyond the travelling distances and a new customer base one other major change is that I now annually advise on over 800 ha of forage maize, mainly going into dairy rations alongside a wide variety of other crops. In my former role I only ever really came across maize as a cover crop for game birds so the last year has been an eye opener“ he confirms.

          Now advising on such a large area of maize presented Adam with a timely opportunity to consider his previous approach to the management of the crop and coincided with the introduction of a new post emergence contact herbicide Gyo (pyridate) that became available to growers and their advisers for the first time last spring.

            “I had always felt that the speed of knockdown was missing from maize chemistry. If you can see the weeds have been dealt with quickly it gives you greater confidence that the job has been done. Maize can often be an unpredictable crop that experiences patterns of extreme growth during very short time periods often putting huge pressure on the timing of post emergence sprays and the chemical combinations in the tank mix. As the maize crop increases in size, so does the amount of herbicide spray that it intercepts at the time of application which can reduce the dose targeted weeds receive .Use of angled nozzles can help improve spray penetration into weeds shaded by the crop canopy, however, it is also vital to look at incorporating new chemistry into the tank mix whenever its available “ he explains.

               Adam decided to trial Gyo last year in place of terbuthylazine partnering the new chemical with both mesotrione and nicosulfuron as a mix and was pleased with its first year performance. After applying a pre-emergence herbicide of straight pendimethalin at 3 l/ha he went with 0.5 - 0.75 l/ha of Gyo in with the post emergence tank mix keeping water volumes high at 200 l/ha to ensure the correct coverage levels.

                “A good pre-em is always crucial and pendimethalin is economic, efficient and takes the pressure off the timing of the post-em applications. In my new area where dairy farms are almost wholly reliant on contractors for spraying that flexibility can often be vital. Trialling Gyo was a smart move and I noted faster and more effective control of many problem weeds such as cranesbill, mayweed, fat hen and nightshade than had been the case using terbuthylazine. The mesotrione in the tank mix continues to give the additional 3 – 4 weeks of residual activity on the weeds that is so important “he adds.

                Following the successful wide scale trial Adam was able to make the following observations on best practice use of the new contact herbicide.

      “Although the manufacturer gives clear guidance on applying Gyo on maize plants at between 2 and 8 leaves of the crop, I believe it is also very important to look at the actual weed size rather than just considering the plant size in isolation when you make the decision on when to spray. Water rates must be kept high to maintain coverage and crop safety levels. With no following crop restrictions, it gives great flexibility and this clearly narrows the risk for any following crop. Going forward I will continue using Gyo at 0.5 – 0.75 l/ha in the tank mix although when encountering larger weeds or coming up against very serious cases of fumitory, cranesbill or nightshade I would be inclined to go with the higher rate and apply the post em spray’s earlier. With the likely loss of terbuthylazine soon, it is great news to find another effective tank mix partner“ he concludes.


Please contact us for more information:

Pearce Seeds LLP
Rosedown Farm
Marston Road

Tel: 01935 811 400
Fax: 01935 816 800