Crop Scene Investigation - 24: Why has Stan's wheat stalled?
Tuesday, March 2, 2010
by BERNARD TOBIN
During the winter months, crop consultants such as certified crop advisor Mervyn Erb spend much of their time sharing the latest crop management insights with growers in preparation for the coming season.
"It's great when growers come to a presentation, listen to your advice and act on it," says Erb. But even the best advice can fall flat if growers are not careful and stray from best practices.
This was the case in August when Erb received a call from Stan, a Grey County grower, who had heard him speak at a meeting during a cold day last winter. "The grower recounted how I had shared my thoughts on using fungicides in wheat and the role they can play in disease control and enhancing straw quality," says Erb.
Stan followed Erb's advice with conviction. He sprayed a Folicur/Proline fungicide combination for head blight control and was also looking to prevent diseased leaves from falling off prematurely, which would contribute to higher quality straw. But that's not how things transpired. The crop's growth stalled several days after Stan applied the fungicide in mid June. The plants grew very little and the heads remained at the same stage, just clear of the flag leaf.
"Stan remembered that I had said the straw would stay greener than usual as a healthier plant lives longer, so he shouldn't rush harvest. However, as time went on, he noticed the heads were not filling, so he looked me up and gave me a call in the second week of August," says Erb.
"When I saw the field, I knew it had somehow suffered spray injury. Most of the spikelets had no kernel in them. The colour of the plants looked fine, but the heads were small and when you shelled them out there was next to nothing – they were empty. The job now was to figure out what had happened. Folicur and Proline fungicides are safe products on wheat, so there had to be something else in Stan's tank.
"Stan's weed control didn't concern me. The 23-acre field had been sprayed with 250 millilitres of Pardner and 50 millilitres of MCPA 500 plus the fungicide Tilt. Stan had followed my advice and combined his fungicides and weed control in a single application, which was a good decision for early disease control and did not impact the crop.
He parked the sprayer after applying the weed control with about 90 to 115 litres (20 to 25 gallons) remaining in the tank, enough to spray about two acres.
"Stan said he later applied his Folicur/Proline when about 25 per cent of the main heads plus tillers were in flower, which is good timing. He simply went back to the sprayer, added Folicur/Proline and headed to the field. I asked him if he had cleaned out the sprayer before he sprayed the Folicur.
"After a few moments, he confided that he had never actually got around to it. He had planned to clean it because he needed to spray Roundup on his Roundup Ready corn, but that never happened because he hired a custom applicator to spray the corn.
"With only 20 to 25 gallons remaining in the sprayer, and a good portion of it Tilt fungicide, Stan thought there was no way it could injure the crop. After doing some quick math in my head, I was pretty sure I knew what had happened, but I wanted to inspect the crop with Stan to be sure.
"As we walked through the field we discovered a narrow, weed-free strip of wheat that Stan had obviously missed when he sprayed the Folicur/ Proline application. Here was the proof I needed. The wheat in this strip was perfect."
Do you know what product in Stan's tank caused the injury and why? Send your solution to Better Farming at: rirwin@betterfarming.com or by fax to: 613-978-5993.
Correct answers will be pooled and one winner will be drawn for a chance to win a Wireless Weather Station. The correct answer, along with the reasoning followed to reach it, will appear in the next issue of Better Farming. BF