John Jackson, Farms Manager for Severn Trent Water Ltd in Nottinghamshire, Derbyshire and Warwickshire, grows continuous maize on some parts of the farm for biogas production. He grows maize on land, close to the River Trent and destined for an anaerobic digester – one of the largest Energy Crop Anaerobic Digestion plant in the UK - which then produces electricity and heat for Nottingham’s sewage treatment works.“On land close to the river, the soil has a history of sludge and organic manures, making it highly fertile and hence unsuitable for many winter crops which would lodge easily. The Trent Valley is also prone to flooding, again making it unsuitable for winter plantings. Spring crops are much better suited to this free-draining, fertile land and maize, in particular, has been a successful crop for us. We plough the land as early as we can and then, once dried out, apply glyphosate to reduce the grass-weed burden. We grow a number of maize varieties with a range of FAO numbers (a guide to maturity, the lower the number, the earlier the maturity) to spread our workload and to suit a long window of harvesting from the third week in September through to mid-November. Crops are drilled from mid-April onwards when the soil temperatures become suitable,” he explains.John explains that the later maize varieties with an FAO of between 230 to 240 usually produce a higher yield of between 10-20% extra. “What we are aiming for is high Dry Matter Production (which is closely linked with energy yield/hectare) ideal for the biodigester. The earlier drilled maize can come off at 40 t to 45 t/ha at 32% DM and the later maturing varieties as high as 60 t/ha. We supply the majority of maize for the biodigester, but it is supplemented by maize purchased from other local farmers too.” In 2010 Severn Trent Green Power Ltd invested £15 million in the plant at Stoke Bardolph, Nottingham. The anaerobic digester, which takes in crop silage grown on its farms estate, produces biogas which is 56% methane which is then used to produce 15GWhrs of electricity a year, equivalent to supplying around 5,000 homes. Since then the plant uses an increased amount of maize silage, rye silage and energy beet producing 20.7GWhrs of electricity. “The digestates at the end of the process make good natural fertiliser which is re-applied to the land for next year’s crop, completing the sustainable cycle,” says John.Eyespot (Kabatiella zeae) is the main disease problem on the farm, says John Jackson. “We have a history of eyespot on the farm as it is a disease that thrives when cold and wet and is spread by the maize trash. We normally plough to reduce trash, but I am interested in the trials that BASF are doing using Comet 200 (pyraclostrobin) to reduce this disease. This fungicide should only be used when weather conditions dictate it will be needed, however.”Where it is cold and wet, normally in the North and West, the main disease in forage maize is eyespot, says John Burgess of KWS, a leading plant breeder for maize.Kabatiella tends to attack the maize crop early from the 8th leaf onwards, with symptoms only appearing at a more advanced vegetative stage. It is unrelated to eyespot seen in cereals. Spores are spread by the wind and via trash and the disease thrives in colder temperatures and high air humidity. It is seen on the crop as small colourless spots with brownish red centre and yellow halo. The leaf blade dries out from the bottom. By reducing the leaf area that is able to photosynthesise, the disease can cause very significant losses.“Comet 200 will give good control of eyespot in maize. I have seen it to be commercially responsive in the field and in trials. There are very few, if any fungicides now registered for control of this disease in maize, with some products being revoked recently,” says John.In the East where it is drier and warmer Helminthosporium can be important, particularly in maize grown for biogas. Initially this is seen as spot-like lesions on the lower leaves underneath the ear. As disease progresses, spindle-shaped oblong lesions parallel to leaf veins appear and eventually coalesce to destroy the leaf. High yield losses can occur with early infections, and if 30% of plants are affected, the use of a fungicide programme is advised.
“You sometimes get rusts, every one year in five, and Comet 200 will control all three diseases. It also has an additional physiological impact by increasing greening, but without changing maturity or dry matter levels,” says John Burgess.Having viewed a farm scale fungicide trial in Nottinghamshire, the differences between treated and untreated were incredible, says BASF’s Ruth Stanley. She has been over-seeing a field scale trial on the KWS hybrid variety Ambrosini where Comet 200 (pyraclostrobin) was applied once or twice in maize to combat diseases such as Kabatiella and Helminthosporium.On inspection she found that in the untreated crop, the cobs had not filled all the way to the top and there appeared to be a lot of disease on leaves. In the section where Comet 200 was applied once early (in July) at 1l/ha the cobs had filled better and were bigger, and there was only a little disease seen. Where Comet 200 was applied late (as late as you dare to go through the crop in August), the level of disease was the same as the earlier treatment and the cobs were similar size. However, where Comet was applied twice, the crop was taller with more foliage, greener and there was very little obvious disease. When it came to cobs, they were noticeably longer and had filled out completely. Comet 200 has an Extension of Authorisation for minor use (EAMU) in maize with a maximum individual dose rate of 1.25 l/ha and a maximum of 2 treatments per crop. It can be applied up to tassel/silk visible stage (BBCH 51-59). Applications are made using a horizontal boom sprayer in a minimum water volume of 200 litres per hectare. Comet 200 is an effective fungicide for the protection against eyespot and will also provide physiological effects in the absence of disease, plant health and greening.Maize is an uncompetitive crop with poor rooting and weeds must be controlled during the early establishment stages in order to avoid early weed pressure adversely affecting yield and quality. “Robust and early weed control at or before the cotyledon stage is advised,“ says Ruth Stanley.Wing-P fits the bill here, she says. “It is predominently a pre-emergence herbicide, but can be used post-emergence if required and is a co-formulation of two active ingredients, dimethenamid-P and pendimethalin. The result is a wider weed spectrum and longer lasting activity. The product also picks up some weeds that are not included on the label such as Crane‘s-bill which is a problem weed in maize with few other options to control it.“