As I mentioned last week, ducks have been doing quite a bit of damage in water seeded rice in south Louisiana. Some farmers who have a lifetime of experience in lower Vermilion parish have told me they have never seen Teal down here this late and in these numbers. In our verification field pictured below it was a mixture of Teal and Black Bellied Whistling Ducks. After publishing last week’s Field Notes I was contacted by personnel at the USDA/APHIS Animal Damage Control office in Crowley. They wanted to know about the Black Bellied Whistlers because they too have noted a huge increase in their numbers this year.
The left most photograph shows an overall view of the field. The areas that appear to be clear water are slightly deeper (very slightly) areas that the ducks found more attractive. There is some rice remaining as can be seen in the second photograph which can be compared the third photograph of the green areas. The grower applied Avipel treated seed after last week’s visit and that seemed to run the ducks out. Others have told me it did not deter Teal. Reports are fairly constant that the product definitely works on blackbirds.
It was too late to start over. We will just have to live with the situation and hope some of the seed treated with Avipel add a little to the stand
Sebe Brown, Dr. David Kerns, LSU AgCenter Entomologists, Dr. John S. Kruse, Cotton and Feed Grain Specialist
This week, Dr. David Kerns and I scouted corn fields at V1 in Evangeline Parish for cutworm damage. Cutworms are usually problems in reduced tillage or no till fields that received a late burndown application leaving weed hosts. However, the fields we scouted were very clean and above ground damage was evident with clipped leaves and larvae being easily found on the tops of rows. Starting clean can help alleviate many problems from early season insect pests; however, clean fields should be routinely scouted for cutworms.
The largest amount of the damage was found in non-Bt refuge corn. Fortunately, the larvae were feeding above the soil surface clipping early leaves and not burrowing down to the root zone damaging the growing point. Seedling corn (up to V4) can withstand injury from cutworms as long as the growing point has not been damaged.
Thresholds for cutworms in Louisiana corn are 6 to 8% damage from above ground cutting or 2 to 4% from below ground boring. With cooler weather moving into Louisiana, cutworms may be located closer to the soil surface in seedling corn. Warmer weather drives the cutworms to burrow down deeper into the soil increasing the risks of having corn injured at the growing point.
Insecticide seed treatments should not be expected to give adequate control of cutworms and Bt technology can provide some protection. VT3 Pro, VT2 Pro, Herculex and SmartStax technologies should help reduce cutworm injury: however, large larvae may overcome these traits. Large larvae are less susceptible to Bt toxins than small larvae.
If an insecticide application is deemed necessary, a relatively low label rate of a pyrethroid will reduce cutworm injury. Bifenthrin would be a good choice due to its soil activity.
Last week we were called to a hybrid rice field where there were issues with stand loss. We could not determine any specific cause, but did note the presence of thrips on nearly every plant. While the number was fairly large there presence was not especially alarming to me because I have always seen them on seedling rice. The field was treated with Dermacor which is not expected to control thrips. We also suspected some seedling disease. In the past we planted at high enough seeding rates to compensate for seedling loss, but the low seeding rates of hybrids magnifies any stand loss. Without a definitive cause we could only make a couple of suggestions; apply an insecticide or add some starter nitrogen. I followed up with the farmer who said he chose to add starter fertilizer and while the stand is still thin the seedlings are growing better. Nearby crawfish ponds may have had some influence on the decision.
We have not had to recommend an insecticide to control adult rice water weevils in several years, but yesterday we were called to a field where I took these pictures. They were in a field of water seeded Cheniere that was drained, but still damp at the time of the visit. The heavy feeding pressure is very evident as was some seedling disease.
The combination of the two was resulting in seedling death and stand reduction. To add insult to injury, the field had been hammered by hail about a week before. It was clear the plants could not take much more. Ironically, the field was planted with Dermacor treated seed which will control the larvae very well while having little to no impact on the adults.
There were so many adult weevils that while kneeling down in one spot I was able to count no less than 5 weevils. We could find them on the soil moving from plant to plant in the middle of the day when they are usually hiding in cracks in the soil. The farmer mentioned he had been under some security lights a few nights before and he had seen thousands of weevils flying around. We recommended a foliar insecticide.
Our verification field in Vermilion parish is presenting several problems which will make for an interesting and challenging year. It is a field with a history of Newpath resistant rice, both red and outcrosses. It was left fallow last year and plowed several times. This year we water seeded Cheniere. As many farmers are experiencing this year, water seeded fields are being decimated by ducks. Most of the farmers I have talked to say Teal are the primary problem, but in our field it is Black Bellied Whistling ducks. I have never seen that many together. Wednesday morning there were well in excess of 100 in a 40 acre block. Any ridge or edge of the field has accumulated the evidence of their feeding as can be seen in the accompanying photograph. One farmer told us that he cannot keep his propane guns going because neighbors turn them off at night.
The accompanying photograph is of Command injury to drilled Cheniere. The farmer applied the herbicide himself using a well calibrated ground rig. He was able to associate the injury pattern with the first pass of each of two loads he applied that day. We discussed the situation with Henry Stefanski, the FMC representative in an effort to understand why it happened. The problem likely occurred in the process of loading the spray rig. Command 3ME is heavier than water. If the agitator was not running when the herbicide was added to the tank even though there was water in the tank the herbicide settled to the bottom of the tank where a larger dose was drawn into the sump and boom before it could be mixed thoroughly. Thus the first pass of spray contained a higher than desired dose of herbicide resulting in the injury. It also means the remainder of the area sprayed probably has less than the intended amount applied to it.
Even though there is considerable bleaching, long term consequences are not expected to be severe. We recommended that he keep the field moist, but not establish a flood until the new leaves are coming out green. It also means no other herbicides can be applied until recovery is observed. In this case the direct effects may not be as great as the indirect especially if broadleaf weed pressure becomes heavy before recovery is evident.
Vermilion Rice Grower, Dwight Hardee of Gueydan is taking part in a field demonstration of the N-Sta*R test. His 15-acre field is divided into three nitrogen treatments based on
University of Arkansas nitrogen soil test recommendations.
Treatment 1: 95% relative yield–65 units of Nitrogen
Treatment 2: 100% relative yield–95 units of Nitrogen
Treatment 3: Standard Farmer Practice–95 units of Nitrogen plus an
additional nitrogen application at green ring
–2/9/12: burn down with 1.5 pt 2,4-D, and 1 qt. roundup
–3/7/12: no-til drill planted into bean stubble CL151 at 50 lbs to the acre. Seed was treated with dermacor/cruiser/fungicide/AV1011
-3/26/12: 4.5 qts RiceBeaux, 6 oz command, 9 oz newpath
4/10/12– 6 oz command, 4 oz newpath, 1 oz permit Fertilizer applied
(took 4 days to flood)
Urea was treated with N-fix.
All 3 plots received 150 lbs DAP 18-46-0 and 150 lbs of Potassium
Urea was used to make up the remaining nitrogen required.
(83lbs–95% and 150 lbs–100%)
I will keep you updated on the progress of the plots. We hope to visit
the plots at the Vermilion Rice Field Day scheduled for Thursday, July
5th, 2012. We will keep track of the yields when the plots are
harvested. The plots are just to the west of the Hardee drier on
Burnell Road in Gueydan.
Over the weekend Sebe Brown scouted a field in Concordia parish where the stand was being severely reduced by colaspis larvae feeding on seedlings. Problems with this field started on March 16 when the stand began to decline. The plants were described as yellow and stunted. This was a Dermacor X-100 treated hybrid rice field no-till drill-planted at a 23 lbs/acre seeding rate. Surrounding fields were growing nicely. When Sebe scouted the field on Saturday he confirmed that the injury was being caused by Colaspis larvae feeding on the roots of seedlings. The stand was reduced about 40% by this injury. The recommendation was made to establish a shallow permanent flood to avoid further injury. In a situation like this, where the rice isn’t quite ready for a flood, you may lose some injured plants to the flood. The alternative is to wait to establish flood, during which time the colaspis will continue to injure the seedlings and further reduce the stand. Establishment of a flood on the field will prevent further feeding injury by the colaspis larvae and eventually the larvae will die. Note: according to experts in Arkansas it may take up to a month for colaspis larvae to die in the permanent flood. Click here to read more about colaspis. You can watch a video on how to scout for colaspis here. The Dermacor X-100 should provide about 30% suppression of the colaspis infestation. Next season, they will consider using a CruiserMaxx or NipsitInside seed treatment to target control of colaspis. The use of pyrethroids will not provide control of colaspis because they are injuring the crop below the soil line.
I have been receiving reports of true armyworms and chinch bugs in corn. True armyworms will usually move into corn once grass hosts have been exhausted or a recent burndown application has been made removing their primary host source.
Corn planted in close proximity to wheat is also susceptible to damage by migrating armyworms. Infestations are typically found around field margins where armyworms have migrated from a wheat field or grassy area. True armyworm damage gives corn plants a tattered appearance with frass (insect feces) present on the leafs or in the whorl of the plant during active infestations.
Most transgenic corn varieties offer protection against armyworm damage. However, single gene varieties such as Yield Guard and Herculex 1 may be overwhelmed when large populations of armyworms are present. Adverse environmental conditions can influence the expression of Bt genes in corn, and larval size is also a contributing factor for control. Normally large larvae are more difficult to control than small larvae.
As long as the growing point has not been injured, young corn (up to V4) can withstand substantial amounts of defoliation and not see a significant drop in yield. Grass control around fields can help prevent outbreaks of armyworms.
Chinch bugs are small insects 1/5 to 1/6 inch in length, with a black body and white front wings creating a white X when viewed from above. Immature chinch bugs resemble the adults only smaller and lacking wings. Nymphs range in color from reddish brown to black in later instars.
Chinch bugs are typically active on grasses in and around fields and movement to seedling corn is common. Damage by both adults and nymphs causes corn to have a reddish appearance on the stem and leaves.
Continued feeding can cause plants to wilt and eventually die. Corn is most susceptible in the seedling stage when plant growth is slow and conditions are dry. Seed treatments and soil insecticides will typically give an 18 day window of protection after emergence. Once plants have surpassed the most susceptible stage, chinch bug damage becomes less of an issue.
If plant growth is slow and chinch bug numbers have reached 5 or more on 20% of plants 6 inches tall or less, a foliar rescue treatment should be applied to stop injury.
When using ground equipment, a high volume, high pressure sprayer delivering a minimum of 20 gpa should be used. Aerial applications should only be used if ground equipment cannot make it across a field.
If an application is deemed necessary, bifenthrin would be the product of choice for ground and air.
We have recently received reports of corn plants snapped off or crimped and laid over. The injury is most often associated with violent storms producing winds, but not always. “Brittle snap” or “Green snap” is much more widespread in the Midwest and High Plains where high winds can cause substantial damage, but occurs in Louisiana from time to time, particularly during periods of active weather. The damage usually occurs below the point on the stalk where the ear sets, is very visible, and generally results in total yield loss for that plant once the stalk has broken or severely crimped and fallen over. There are several factors that can contribute to brittle snap, including wind speed and direction, growing conditions, and hybrid type.
High wind speed, particularly when it hits perpendicular to the corn rows, is the main factor causing brittle snap. Injury may be more likely to occur during wind downbursts from a storm cloud, creating areas or pockets of damage in a field. If the winds hit during cooler periods of the day when transpiration is reduced and the plant is more turgid, the injury may be more widespread.
Growing conditions can be a factor as well. Warm weather, adequate soil moisture, and high soil nitrogen levels allow for rapid vertical stalk growth from roughly V5 to V18. Rapid cell elongation is occurring – thinning the cell walls – leaving the stalk vulnerable to snap. Inadequate potassium in relation to the amount of nitrogen available may exacerbate thin cell wall issues.
Corn seed producers recognize there are differences between hybrids as to their susceptibility to brittle snap. Some companies take the time to rate and report brittle stalk ratings, and it is worth taking these ratings into account when making seed buying decisions. Thin, rapidly growing stalks, high ear placement, and inherently thin cell wall structure in some hybrids make them more vulnerable to brittle snap than others. It may be that a few hybrids are susceptible enough that equipment (such as a boom) running through the field could knock over the plants, so producers should be aware if this is occurring and consider a different hybrid in the future.