Good Fruit Grower

April 15

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Soils & Nutrients Beware of weed RESISTANCE G Combinations of herbicides can keep resistance at bay. by Geraldine Warner lyphosate has been such a cheap and effective herbicide that there's a risk of overusing it. It's tempting to attach the weed sprayer any time the orchard is being mowed, because it costs very little extra to do the two tasks together, says Tim Smith, Washington State University extension educator in Wenatchee. Some orchardists are spraying four to six times a year. "Every year, almost every orchard gets glyphosate on a regular basis," Smith said. "It's very cheap, and you don't need to put much of it on for it to work." The problem is that weeds are developing resistance to glyphosate where it's been frequently used, warns Smith, who would like to see it used no more than once a year, and only if necessary. And by "necessary" he means when perennial weeds are blowing up. Perennial grasses and broadleaf weeds are susceptible to glyphosate between midsummer and fall. So there is little use in applying it in the spring before many of the perennial weeds are growing. That's why Smith recommends applying glyphosate in October to control the perennial weeds. Follow that with a tank-mix of contact and residual herbicides in the spring (April or May) to catch the new weeds. Residual (preemergence) herbicides leave residues in the ground that prevent weeds from growing. Any weeds that do grow will be controlled with contact herbicides that burn the plants on contact. "If you depend on one kind of weed control, then the weeds that make it through that weed control will become dominant in the orchard, so we like to change up the products we use and have both residual products and contact products in the orchard," Smith explained. In trials, Smith has been able to achieve season-long weed control with this program. 32°, 31°, 30°, 29°, can help! Do these #s worry you? KDL KDL® 0-0-24 DEXTRO-LAC ® SERIES 28° Many tree fruit growing areas of the country experienced multiple and severe frost events in 2012. The extent of damage from a frost event depends on many environmental factors that growers can't control and the steps growers can take to mitigate frost. Irrigating can put heat into the orchard floor and wind machines can be helpful if there is an inversion layer. Foliar applications of KDL can also help condition buds and fruitlets to better tolerate subfreezing temperatures. KDL is a unique sugar-based potassium that when applied within 12-48 hours of a frost event has been shown to help improve frost tolerance and minimize damage. Growers normally should AVOID foliar applications of potassium during fruit cell division because potassium can antagonize calcium during this time and reduce final fruit quality. But when faced with the threat of significant crop loss minimizing the immediate frost danger is the priority. KDL can help! During spring as plants begin to grow new green tissue the demand for nitrogen is at its greatest. At this stage the nitrogen to potassium ratio strongly favors nitrogen. Young tissue high in nitrogen is more susceptible to frost damage. Applying KDL prior to a frost event can change the nitrogen to potassium ratio in the tissue and improve cold tolerance. This spring give your orchard the edge over frost – Apply KDL! Science-Driven Nutrition SM AGRO-K CORPORATION © 2013 Agro-K Corporation. KDL is a registered trademark of Agro-K Corporation. 16 April 15, 2013 GOOD FRUIT GROWER

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