5/31/2011 9:27:06 PM
Today I’ve have four calls about insect problems in rice. Yesterday I ran the battery down on my phone between phone calls, emails and tweeting field observations. Which reminds me, if you are using twitter, you are welcome to follow me @NatHummel for field updates.
These dry conditions are exacerbating problems in drilled rice, which in many cases is dry, dry, dry. We need some rain. The wind is not helping the situation. One consultant, who has decades of experience in rice, called today to tell me he would appreciate more training in identification of uncommon insect problems – namely aphids, thrips and chinch bugs. As we shift away from water-seeded to drill-seeded rice, these insects have the potential to become more common pest problems. It looks like that might be happening this year.
This blog posting will focus on many of those “secondary pests” which we happened to observe in Evangeline Parish yesterday. Before I get to that, just a quick update on what is becoming the chinch bug situation.
In Jeff Davis Parish, I have now heard of four additional locations which suffered from infestations of chinch bugs. This brings the count to about 8 to 10 sites with chinch bug infestations. Some had been treated with Dermacor X-100, but remember, Dermacor will not control chinch bugs. CruiserMaxx and NipsitInside should provide control (refer to previous postings about difference in seed treatments for more details). It has been noted that drilled hybrid rice, planted at low seeding rates, needs to be carefully scouted for chinch bugs. This is true primarily because in a field with a low seeding rate, the number of plants per acre is substantially lower than in field planted at a conventional seeding rate. When an insect (such as chinch bugs) infests a field with few plants to begin with, they can cause substantially more injury more quickly than in a field with a thicker stand.
Chinch bugs can be difficult to scout because they have a habit of hiding in cracks during the heat of the day and also because they often feed at the soil line near the base of the plant. This injury caused by feeding on the heart of the rice plant is what causes the rice to throw a red or orange leaf and eventually die from injury. To treat an infestation it is best to apply a flood or flush water across the field and then follow with a pyrethroid insecticide – this strategy drives the insects up onto the plant allowing them to be exposed to the insecticide.
In Evangeline Parish we found a few chinch bugs feeding on the plants (picture 1).
We also found a mating pair of chinch bugs on the soil surface between the rows. Just to illustrate how difficult these can be to scout, can you find the chinch bugs in this picture (picture 2)?
After mating, chinch bugs will deposit eggs, from which first-instar nymphs will hatch. We did see some first-instar chinch bugs near the base of the plant. The first instars look very different from older stages - are very small and bright orange in color.
Yesterday, Anna and I took stand data at the Evangeline Parish demo test site. Here is the field map. (I’m in the process of building LSU AgCenter websites for each of the test sites, but suddenly time at my desk is precious and rare.) The field is located between Ville Platte and Vidrine at these GPS coordinates: 30°41’42.66?N, 92°24’23.80?W. The plots are flagged with colored flagging according to treatment (picture 4).
The variety XL745 was planted at a 25 pound/acre seeding rate on March 21, 2011. First emergence was noted on April 5, 2011. Yesterday, we visited the site two weeks after emergence to take observations on the stand. At this location we are comparing the three seed treatments (CruiserMaxx, Dermacor X-100 and NipsIt INSIDE) to an untreated check.
In general, there does not appear to be a significant difference between treatments, but the untreated cuts do not look quite as vigorous. We will wait to summarize all the stand count data from all sites before making definitive statements about any effect of seed treatments on the stand vigor. Following is a series of field shots comparing the treated strips (pictures 5 - 10).