Colaspis causing damage in Evangeline Parish

7/30/2010 8:30:56 PM

Each plot is 7 rows wide. Jacob measured the length of all the gaps caused by colaspis. At the end of the season we will take yield.

Misses in drill rows were caused by colaspis larvae feeding at the base of the plant.

Colaspis larva that was found feeding on the base of a rice plant.

Colaspis causing damage in Evangeline Parish

Today I met Dr. Dustin Harrel (Rice Agronomist, housed at the rice research station at Crowley) at his agronomy test plot location in Evangeline Parish. Dustin had called me last Friday because he was seeing stand reduction in his test plots and found that colaspis larvae were causing the damage. I recommended that he put a flush across the field immediately. The field was flushed and then we had to wait for it to firm up to take some data on the damage caused by the colaspis.

Today, we evaluated the plots and decided the best way to start to assess damage would be to measure the length of the gaps where plants were killed by colaspis larvae feeding on the roots. Dustin’s assistants – Jacob and Ron – graciously assisted with the measuring of the gaps.

It was not hard to find the damage in the field, but it did turn out to be hard to find the culprit.

After much persistence in searching (while we measured gaps) Dustin found a colaspis larva in one of the plots on the edge of the test area.

Dustin has agreed to let us monitor the colaspis damage in 12 of his test plots. These plants were grown from seed treated with Dermacor X-100. Unfortunately, we do not have any plots in this test treated with CruiserMaxx or untreated for comparison. As usually happens in science, colaspis have not caused any damage in any of my “planned” test plots. I am hoping we will learn more about the biology of this pest in these test plots. One thing we have already learned from this location is that a flush really did help the situation. When he first saw the damage in the plots, Dustin said the plants were producing red leaves, almost like they had suffered herbicide injury. Now, those damaged plants are hard to find because they have dried up and died. The rest of the plants seem to be doing very well.

We will continue to monitor these plots for the duration of the season. This site will also be a tour stop on the Evangeline Parish Rice Tour, May 25, 2010. Please check the blog for an announcement about the tour. If you’d like a refresher on how to scout for colaspis please view the scouting video posted at the LSU AgCenter website, or the powerpoint presentations posted from the training we conducted in May 2009.

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