Today’s blog is a little long, which is appropriate for a LONG day in the field. I will describe a complex field call and how we assessed the problem. Would appreciate your thoughts on the posting.
Today we scouted a field in Concordia Parish with County Agent Glen Daniels. This field is being farmed by first-year rice farmers Bart and Toby McIntosh. The consultant is Clayton Fairbanks. About a week ago they started noticing plants dying in their newly established stand of CLXL745 rice. This is a real concern, especially with the low seeding rates recommended for the hybrid varieties. Bill Williams was called in because they suspected it was caused by herbicide injury. It was concluded that herbicide was probably not the issue (the field has received 1 to 8 command, .5 oz first shot, and roundup). A flush was advised on some cuts to see if it helped the problem. Unfortunately, the problem became worse in areas that were flushed. Bill thought thrips might be the culprit, so Glen asked me to check the field.
By this time, there are a lot of dead plants in the areas of the field that were flushed. Some plants are still dying, but others appeared to be recovering.
We looked closer and also examined some weeds in the field on the margins and were easily able to find thrips on the plants.
These thrips are hard to scout for, and very tiny in size, but with a trained eye and some patience they can be found. We need to mount specimens on glass slides and get them under a microscope to identify the species.
Thrips damage the leaf by feeding with rasping mouthpart which causes the plant cell to dessicate (dry up).
The damage from the thrips appears to be compounded by damage from rice water weevil adults feeding on the young rice.
The thrips and rice water weevil feeding damage was compounded by early-season cool weather conditions which causes plants to grow more slowly. Interestingly, this field was grown from seed treated with Dermacor X-100. Unfortunately, none of these insecticide seed treatments are a silver bullet. In hindsight, with this combination of pests CruiserMaxx would have been a good option. Dermacor is an excellent product for rice water weevil larval control, borers, leafminers, and south american rice miners. Dermacor does not have the ability to control chinch bugs, thrips and is marginally effective against rice water weevil adults.
Based on the amount of damage from thrips and rice water weevil adult feeding, and the fact that a permanent flood is still about two weeks off, I recommended an application of Karate to prevent further damage. Once a flood is established, the Dermacor should provide effective control of rice water weevil larvae. I’ll keep tabs on this field and let you know how it progresses. (All photos taken by Anna Meszaros)