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Manage carefully to avoid unintentional crop damage.

Agronomy Bulletin 122 - Corn Herbicide Injury

Visual characteristics of herbicide injury on corn.

Situation

Crop injury can occur from pre- or post-emergence corn herbicide application. It usually occurs due to poor application timing, improper application rate, carryover from the previous year’s application or leftover residual in the spray tanks, lines and filters. Fortunately, yield loss, in most cases, is minimal. Be aware of herbicide injury symptoms and ways to prevent them.

Factors to Consider

  • Field patterns
  • Application timing
  • Corn growth stages
  • Equipment cleanliness

Action Plan

  1. PROPERLY DIAGNOSE DAMAGE. Many visual signs of herbicide injury can be confused with other issues, such as above-and below-ground pests, nutrient deficiencies and/or toxicity, as well as saturated soils. To diagnose appropriately, growers and crop advisers should consider the timing of recent herbicide applications, herbicides applied (this year and last year), and other fields in the area exhibiting a similar injury. There’s typically a pattern when dealing with herbicide injury. Irregular shapes are associated with a biotic factor; striping and geometric shapes are usually man-made.
  2. PLAN HERBICIDE APPLICATIONS. Misapplication of herbicides outside the labeled window can result in issues with germination, ear development and pollen shed. Review the label for best application practices, including the appropriate stage of growth for application. Stressing plants at specific stages of growth can have a negative impact on ear formation and yield potential. Unfortunately, if corn incurs severe herbicide injury – from pre- or post-emergence application – there is no real cure. Growers should consider the health of their crop before applying herbicides. Stressed crops have a harder time metabolizing herbicide applications, which may increase the likelihood of crop injury.
  3. FOLLOW PRODUCT LABELS. With so many types of herbicides on the market, growers and custom applicators should carefully read herbicide labels – not only for application timing – but also for rate and mixing instructions. Excessive use offers no benefits and can be detrimental to this year’s crop and subsequent crops. Always apply crop protection products in the right amount, under the right environmental conditions and at the right stage of crop growth.
  4. MAINTAIN CLEAN SPRAY EQUIPMENT. Leftover residues from crop protection chemicals in spraying equipment and nozzles also can cause crop injury. Custom applicators and growers should thoroughly rinse their spray equipment when switching between different crops and/or herbicide active ingredients.
  5. PREVENT HERBICIDE DRIFT. Drift is often to blame for herbicide injury. Wind can carry herbicide particles that burn the outside of nearby fields. Check weather conditions before applying herbicides. Many of today’s herbicide labels will have wind speed recommendations and limitations – make sure to review.

Summary

Careful management is the best way to avoid crop injury from herbicides. While there’s no remedy for herbicide injury, corn crops can often recover and still perform well. To avoid crop damage, read herbicide labels, apply during proper growth stages and avoid windy days. To view images of herbicide injury, click here. For more information, visit our website or contact your local Mycogen Seeds commercial agronomist or trusted agronomic adviser.

Resources

Published on Tuesday, July 19, 2016