Continued dry weather takes its toll on Indiana forage crops

WEST LAFAYETTE, Ind. - Indiana's forage crop yields aredown and won't likely improve without decent rainfall in the near future,prompting a need for growers to take precautions to avoid further crop loss,says a Purdue Extension forage specialist.

Forages initially were damaged during hard freezes inApril and have struggled to yield amid the unrelenting hot, dry weather of Mayand June.

"Many producers have reported to me that their firstcutting was reduced fairly substantially as compared with other years - down by25 percent or more," Keith Johnson said. "So we're starting out in adeficit in terms of total-season hay production possibilities. Then we couplethat with the dry weather and the next harvest doesn't look to be superhigh-yielding either."

The April freezes damaged alfalfa tillers and, as aresult, not only was the first cutting reduced, but if harvested prematurelythe crop could have been lacking in carbohydrate reserves needed for the nextcrop to regrow. Harvesting second and subsequent cuttings before the plantshave time to rebuild vigor could cause stands to suffer into the future.

Johnson recommended waiting until just after late bud oron into some flowering before harvesting alfalfa.

"If we've harvested relatively early a couple oftimes, we really have put some stress on that plant," he said. "Weprobably should give it an opportunity to get beyond late bud and maybe intosome flowering to give us more days to put carbohydrates into the reserves inthe crown and taproot. Then there should be enough vigor for regrowth."

In addition to delaying harvest a bit, Johnson also saidnow is a good time to look at soil fertility. Soil tests can reveal anynutrient deficiencies and help producers know which fertilizers need to beapplied.

But Johnson cautioned producers against applying nitrogenin hay and grass-dominant pastures until there is enough moisture.

"I think we have to recognize at this point moistureis the yield-limiting need," he said. "I would hold off on nitrogenfertilizer application until we return to the more timely and sufficient rainswe need for grass production to occur."

The lack of rain also has created conditions thatexaggerate potato leafhopper damage. The insect feeds on alfalfa and many otherplants. During feeding, it injects the crops with toxins that stunt growth andlimit yield.

Johnson encouraged growers to scout for the potatoleafhopper with a sweep net intended for this pest. Insecticide treatmentscould be warranted when the average number of potato leafhopper in a singlesweep of the net is 0.1 leafhoppers per inch of alfalfa height.

For example, an alfalfa crop 10 inches tall would needmore than one leafhopper per sweep to warrant control. Those insecticides,however, also kill beneficial insects.

A better option, Johnson said, is for growers to plant aleafhopper-resistant variety the next time they seed the field.

Finally, growers need to pay attention to harvest dates toavoid harvesting forage crops too late in the season.

"If enough stresses occur, growers really need to beaware of when they harvest the last crop," Johnson said."Traditionally, for those in the northern part of the state, somewherearound Sept. 5 should be the last growing-season harvest. For those in southernIndiana, we probably can stretch that to around Sept. 15.

"This allows enough time to build those carbohydratereserves before a killing freeze comes along, so we have a plant with a full tankof energy through the course of winter. And then, as we break dormancy thefollowing year, enough reserves are there for a vigorous break winter dormancycrop."

Writer: Jennifer Stewart, 765-494-6682, jsstewar@purdue.edu

Source: Keith Johnson, 765-494-4800, johnsonk@purdue.edu

Ag Communications: (765) 494-2722;
Keith Robinson, robins89@purdue.edu
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