April 27, 2011 - Bill bugs and chinch bugs reducing rice stands in Calcasieu Parish, Part 2

6/2/2011 9:16:42 PM

Picture 1. The “windshield view” of chinch bug injury in a field of CL151 in Calcasieu Parish.

Picture 2. In this field the injury was not progressing in from the edges as we typically expect with chinch bug injury (refer to posting of injury in Evangeline Parish in the 2010 field season).

Picture 3. Healthy rice plants that are just starting to show injury, bordered by dead and dying rice plants.

Picture 4. As we pulled up dead and dying plants, we found hordes of chinch bugs in the soil near the roots.

Picture 5. First instar chinch bugs are bright orange in color with a tan band on the back.

Picture 6. Chinch bug adult at base of plant – note the black and white color pattern that gives the appearance of an hourglass.

Originally posted April 27, 2011, by Natalie Hummel on Louisiana Rice Insects

On the same day, next we looked at a field with the most severe infestation of chinch bugs I have ever witnessed. The field of CL151 was drilled at 70 lb/acre with Dermacor X-100 and a fungicide package. The soil was moist, and in some places there was standing water – from this morning’s rain storm (picture 1). Unfortunately it looked like our nice rain storm this morning did nothing to decrease the chinch bug population. In the higher elevations of the field we had no trouble locating high populations of chinch bugs below the soil and feeding on the roots of the plants. It was easy to spot the injury from the truck.

The consultant (Randy Verret) found it as he walked across the field and started to find patches of dead/dying plants. Upon further inspection, Randy found chinch bugs of all stages attacking the plants. The injury is clustered in patches across the field (picture 2).

Healthy rice plants that are just starting to show injury, bordered by dead and dying rice plants (picture 3). What is happening is the chinch bugs are moving from dead plants to healthy plants. Most of the dead plants had almost no roots left – they were easy to pull out of the ground. The chinch bugs appear to be feeding on the roots and also on the leaf sheaths near the soil line.

As we pulled up dead and dying plants, we found hordes of chinch bugs in the soil near the roots (picture 4). This field was infested with all life stages of chinch bugs, ranging from nymphs to adults (picture 6). Recall that chinch bugs have incomplete development – thus they shed their skin to grow to the next life stage and each stage looks different in appearance from the other. All stages feed on rice plants and have the ability to cause injury. First-instar chinch bugs are bright orange in color with a tan band on the back (picture 5).

In light of such a severe infestation and ongoing plant death, we recommended an application of a pyrethroid as soon as possible to prevent further stand injury. After application of permanent flood this rice will be protected from rice water weevil injury by the Dermacor X-100 seed treatment. If everything was prepared to go to permanent flood immediately, that would probably be sufficient. Flooding removes the chinch bugs from the root zone of the plant, preventing further injury. In this particular field it will be about a week before permanent flood is established, and I fear that the chinch bug injury could progress quickly during that time. Aggressive scouting and a quick response will hopefully save this stand from further reduction. I hoped that the rain we had this morning (in some cases near 4 inches) would halt the chinch bug problems, but as you can see here, that does not appear to be the case. Vigilant monitoring is still needed.

Tomorrow we will plant our final rice water weevil demonstration site in Avoyelles Parish.





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