Sugar Producer

May 2010 Sugar Producer

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impact the surrounding soil rhizosphere. Much of his research has focused on how glyphosate can monkey wrench several of those processes. “Glyphosate interferes with the plant’s ability to pick up zinc or man ganese from the soils,” says Dr. Huber. “That’s unfortunate because early nutrient uptake is critically important for sugarbeet root growth, but also for resistance to soil-borne diseases like Fusarium and Rhizocto- nia. Any lag in the period when the crop needs manganese and you have increased disease susceptibility and reduced yield potential.” He notes that plant tolerance to stress and many pathogens is dependent on a full suf- ficiency of micronutrients to maintain impor- tant physiological processes. It’s this balance Spencer says he set out to accomplish when he started using the new foliar manganese and zinc. Spencer has about 600 acres of his own ground plus additional acreage he custom-farms for others. He always has at least 100 acres of sugarbeets, and often more than that depending on the rotations. In 2008, he split a field with the Sysstem-Ready and liked the result. Last year he used it on all his beets, plus his corn and dry beans. “It’s not just the increases in the tons and the sugar,” says Spencer. “The beets didn’t seem as stressed. They matured faster, stayed greener and looked more vigorous. We sprayed Sysstem-Ready after a hail storm, and it seemed like they came back quicker. In some fields, you can’t really see that there will be more yield, but if you pull a few feet of row and weigh them, you’ll see the difference.” LIMITED SOILS The Spencer fields are west of Scottsbluff and toward Torrington, Wyo. Ian Crawford, another Simplot field development agronomist, notes that he has seen similar results among the growers he works with in Idaho. “They are using Sysstem-Ready in both Roundup Ready and conventional crops in addition to their sugarbeets,” says Crawford. “The vitality and the yield increases are getting a lot of attention. But there is another important aspect of nutrient management in our region of the country. “Our high pH soils in the western U.S. have us at somewhat of a disadvantage from the be- ginning because they’re already limited in zinc Dr. Huber is a retired plant pathologist and professor emeri tus in the Botany & Plant Pathology Department of Purdue University. and manganese,” says Crawford. “This nutrient system makes good agronomic sense based on those reasons, too, not just because we’re using glyphosate. It’s particularly important if we have cool, wet conditions like we’ve had the past couple of years. We need a fertility program that helps overcome these limiting factors.” He notes that in the rush to adopt glyphosate- tolerant sugarbeets, now at 95 percent of total acreage, producers may be overlooking the important aspects of nutrition related to the herbicide’s impact on plant disease defense systems. “The work that Dr. Huber and others have done is very important,” Crawford adds. “Many pathologists rarely research or talk about plant nutrition and the impact of disease when nutri- ents are deficient. It’s an area we need to look at more closely. Nutrition isn’t just about NPK. It’s about understanding roles and interactions of all nutrients in relation to diseases.” NUTRIENTS & DISEASE In his recent paper “Ag Chemical and Crop Nutrient Interactions – Current Update” pre- sented at this year’s Fluid Fertilizer Foundation Forum, Dr. Huber notes that glyphosate “inhibits plant enzymes responsible for disease resistance so that plants succumb from pathogenic attack. This also predisposes Roundup Ready and non- RR plants to other pathogens.” He says that by inhibiting enzymes in the plant pathways, the glyphosate makes the plant “highly susceptible to various ubiquitous soilborne pathogens” such as Fusarium, Pythium, Phytothphora and Rhizoctonia. He notes that glyphosate also is a potent microbiocide and is toxic to important beneficial soil organisms that facilitate the availability of soil minerals crops need. “It is not uncommon to see Cu, Fe, Mg, Mn, Ni and Zn deficien- cies intensify and show in soils that were once considered fully sufficient for these nutrients,” he continues. “Increasing the supply and avail- ability of [those nutrients] have reduced some of the deleterious effects of glyphosate on these organisms and increased crop yields.” Dr. Huber notes that one of the positive steps growers can take is to provide adequate nutri- ent availability for full functional sufficiency, which is what Spencer has done. Dr Huber says that residual glyphosate in RR plant tis- sues can immobilize most traditional sources of foliar-applied micronutrients for 8-15 days, an obstacle that has left many sugar beet crops www.SugarProducer.com 19

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