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.
Originally posted by Dr. Natalie Hummel LSU AgCenter Extension Entomologist on her Louisiana Rice Insects blog. The link to the original article can be found here: http://louisianariceinsects.wordpress.com/2012/04/17/colaspis-strike-concordia-parish-rice/
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.
By Sebe Brown, Dr. David Kerns, Dr. Rogers Leonard – LSU AgCenter Entomologists
Thrips are annual pests of cotton in Louisiana. Damage by these insects cause stunted growth, delayed plant maturity and plant death under heavy infestations. Cotton is most susceptible to thrips from emergence to the 4 true leaf stage. Once cotton has reached the 4 true leaf stage, root differentiation has increased, terminal bud growth is accelerated and plants become less susceptible to injury.
The most common thrips found in Louisiana cotton are tobacco thrips, eastern flower thrips, onion thrips and western flower thrips. These insects overwinter on a variety of weed hosts. Planting seasons with windy conditions can have considerable influence on the severity of thrips populations in early cotton. Thrips are typically weak flyers and wind helps to distribute infestations across fields.
Cotton seedlings that experience cool, wet soils develop very slowly and remain susceptible to thrips injury much longer than cotton planted in a warmer, more optimum, environment. This year has been very warm and wet with considerable alternate hosts around cotton fields to produce sources of thrips infestations. With the loss of Temik for the 2012 growing season, insecticide seed treatments (ISTs) and over-sprays will be critically important for controlling thrips on seedling cotton.
Cotton seed comes with a variety of seed treatment options that may either be purchased through a seed company or applied by a dealer downstream. Outlined below are a few of my thoughts with regards to insecticide seed treatment packages on cotton seed.
Dow’s Phytogen seed comes with a base package of thiamethoxam (Cruiser), with Avicta Complete Cotton available upon request. Avicta Complete Cotton includes Cruiser for the IST, multiple fungicides and abamectin for nematode control. Information on Phytogen seed treatment options can be found here.
Monsanto’s Deltapine cotton seed comes with a combination of products that fall within the Acceleron treatment umbrella. The base package in cotton includes imidacloprid (Gaucho) and several fungicides. However there are several options within the Accereleron brand. Be sure that your seed is treated with what was ordered. These options are upgrades to Avicta Duo Cotton with Cruiser for insect control, several fungicides for disease control and abamectin for nematodes. Beware: the Acceleron seed treatment label in other crops may contain other products. More information on Acceleron seed treatment options can be found here.
Bayer’s Stoneville/Fibermax cotton seed comes with a base package that includes Gaucho for insect control and thiodicarb for nematodes that falls under the Aeris treatment umbrella. Producers also have the option to upgrade to Poncho/Votivo with clothianidin (Poncho) for insects and Bacillus firmus (Votivo) for nematodes. More information on Aeris seed treatment options can be found here.
Another option is to buy the minimum insecticide treatment available, and have a dealer apply additional insecticides downstream after the seed is purchased.
IST’s offer limited early season protection from thrips. Effective residual efficacy usually offers 10-14 days of control after plants emerge. Unsatisfactory residual control can occur with these treatments and cotton should be frequently scouted for thrips until the four leaf stage and when cotton plants are actively growing.
During 2011, western flower thrips were a problem in many Louisiana cotton fields. Western flower thrips can be difficult to control with standard applications of acephate, dimethoate, bidrin, etc. Producers also risk flaring spider mites and cotton aphids with repeated applications of broad-spectrum insecticides. Recent research conducted by the LSU AgCenter demonstrated satisfactory control of a complex of species including western flower thrips with Tracer and Radiant at 2 and 7 days after treatment.
The use of a nonionic surfactant with these insecticides can help increase efficacy against thrips. Rescue applications of foliar insecticides should be applied early in cotton development with applications at the 1-2 true leaf stage yielding significantly greater lint per acre than treatments applied at the 3-4 true leaf stage. Do not wait for thrips treatment in an attempt to time an overtop herbicide application.
Insecticide seed treatment options get producers off to a good start when it comes to insect pest management in cotton. However, these treatments should not be relied upon for sole control of all early season pests. IST’s are one of the best management practices (BMP’s) recommended by the LSU AgCenter for cotton IPM.
For more information concerning insect pest management, contact your local LSU AgCenter parish agent, LSU AgCenter specialist, or Louisiana independent agricultural consultant.
by Sebe Brown, Extension Entomologist
All, I have been seeing more instances of true armyworms infesting wheat in the North Louisiana. These include wheat plots at St. Joe and Winnsboro at various stages of growth. Our threshold for armyworms is 5 worms per square foot with foliage loss occurring. If armyworms reach the flag leaf and the wheat has not headed an application should be made. I have also encountered varying levels of stink bugs (primarily rice stink bug) in wheat. Populations of stink bugs have to be high for damage to occur and our threshold is 10% infested wheat heads in the milk stage and 25% infested heads in the soft dough stage. Stink bug numbers will usually be higher around the edges of a field with numbers falling off as you walk further toward the middle. This means you may reach threshold around the edges of a field, but may also be well below threshold 100 feet in. Applications of pyrethroids can control both of these pests.
Rice stink bug photo courtesy of Gus Lorenz
Armyworm larvae on wheat heads photo courtesy of Robert Bellm, University of Illinois Extension
You can link to Dr. Natalie Hummel’s weblog by going to: http://louisianariceinsects.wordpress.com/
This article was originally published in Louisiana Farm and Ranch, February 2012. I’m reposting it here for your information. This is an important article to read as growers are making their decision about insecticide seed treatments in rice for the 2012 season.
Authors: Natalie Hummel, Associate Professor and Assistant to the Director & Mike Stout, Professor
We have had quite a few inquiries about using a combination of seed treatments, neonicotinoid and Dermacor X-100, in rice. While this practice is legal, using more than one seed treatment is not a practice that we encourage in most circumstances because it results in more insecticide use in rice production than may be necessary.
The rice industry is considering one of these combinations of seed treatments: 1) Dermacor X-100 and CruiserMaxx or 2) Dermacor X-100 and NipsitINSIDE. Typically, a combination of seed treatments is only being considered when planting rice at low seeding rates, primarily because of concerns about the lack of efficacy of CruiserMaxx and NipsitINSIDE at hybrid seeding rates (25 lbs/acre or less) that we have observed in our rice water weevil demonstration trials and small plot trials. The second scenario is where Dermacor X-100 is being used for rice water weevil management and there is a history of stand reduction because of a sporadic pest infestation, usually chinch bugs or armyworms. Combining seed treatments provides a benefit of protecting the crop from injury by some primary and sporadic crop pests.
As the rice industry moves toward a more sustainable crop production profile, the LSU AgCenter strongly encourages rice producers to be good stewards of these insecticide seed treatments. Stewardship of these seed treatments means avoiding the use of insecticides not needed in the crop. For this reason, we discourage the widespread use of a combination of insecticide seed treatments in rice. We instead encourage the person making the seed treatment decision to consider the spectrum of pests that each insecticide can control, the seeding rate, and the history of crop pests in that field.
It is important to remember that each of the seed treatments controls a different group of insects. Dermacor X-100 belongs to a class of insecticides called anthranilic diamides, which target a specific receptor in the muscle of the insect. Dermacor X-100 is registered to control rice water weevil larvae, borers (Mexican rice borer, Rice stalk borer, Sugarcane borer), armyworms and colaspis (2ee registration for suppression). CruiserMaxx and NipsitINSIDE are both neonicotinoid insecticides that affect the nervous system of target insects. CruiserMaxx is labeled to control rice water weevils (larvae and adults), chinch bugs, colaspis and thrips. NipsitINSIDE is labeled to control rice water weevils and colaspis. We do not have data to support the ability of CruiserMaxx or NipsitINSIDE to control chinch bugs, colaspis or thrips in Louisiana, but we anticipate that they will control these pests based on observations from other crops and from rice in other parts of the world. As you study these seed treatments, you can see how a combination of these products can control most of the insects that attack rice in Louisiana. This is part of the reason why there is an inclination toward using a combination of treatments.
Here are criteria for you to consider as you make your seed treatment decision. The first is the seeding rate. This needs to be considered because neonicotinoids don’t always provide good control of rice water weevils at low seeding rates. Dermacor X-100 does provide control of rice water weevils at all seeding rates, but it will not control chinch bugs or thrips. According to the chemical manufacturers, neonicotinoids do control other early season pests including chinch bugs, thrips and colaspis. Another challenge at low seeding rates is that the plant stand is thin and is less tolerant to any insects that reduce the stand by killing seedlings. Insects that can reduce the plant stand count include armyworms, chinch bugs, colaspis and thrips. Borers can infest fields after the plant is at the green ring growth stage and reduce yields by causing deadhearts and whiteheads. Remember that if you put out a combination of seed treatments for a sporadic pest and that pest doesn’t infest your field, then you didn’t need to use a combination of seed treatments. We have data that indicate that rice water weevils infest more than 90% of rice fields in Louisiana. This justifies the use of a seed treatment to control rice water weevils as part of a good IPM program. That is not the case for many of our sporadic pests (armyworms, chinch bugs, colaspis, borers, etc.), which rarely occur at levels that justify treatment. Also, keep in mind that we rarely recommend an insecticide treatment for thrips in rice; usually the damage is not severe enough to require an insecticide.
Here are a couple of situations where a combination of seed treatments may be a good management decision. If you are planting rice at a low seeding rate and you anticipate that you will have an infestation of chinch bugs that would justify a pyrethroid treatment, then a combination of seed treatments would be a good option. In this situation, you would be using Dermacor X-100 to control rice water weevils, borers and armyworms and adding a neonicotinoid to control chinch bugs or thrips. Also, if you are planting rice at conventional seeding rates and you are using a neonicotinoid seed treatment to control rice water weevils and colaspis, but you typically have problems with armyworms or borers, then you may want to apply Dermacor X-100 to your seed.
There is one more thing to consider as you make your seed treatment decisions for the 2012 season. The EPA recently approved a Section 24C (special local need) registration for use of Dermacor X-100 in water-seeded rice. If you are interested in this option, a certified seed treater can provide more information. Remember that you CANNOT use the other seed treatments (CruiserMaxx or NipsitINSIDE) in water-seeded rice. The use of CruiserMaxx and NipsitINSIDE in water-seeded rice is illegal and will not provide control of the target pests.
If you have any questions about the seed treatment options registered for use in rice, please contact your local County Agent, or Natalie Hummel (firstname.lastname@example.org) for more information.
Sebe Brown, Extension Entomologist
Selecting corn seed treatments can be a challenging and expensive undertaking faced by many producers across Louisiana. Corn seed treatments target three spectrums of pests: nematodes, fungal seedling diseases and insects. This article will address insecticide seed treatment options available for corn.
Insecticide seed treatments are usually the main component of a seed treatment package. Most corn seed available today comes with a base package that includes a fungicide and insecticide. The insecticide options for seed treatments include Poncho (clothianidin), Cruiser/Cruiser Extreme (thiamethoxam) and Gaucho (Imidacloprid). All three of these products are neonicotinoid chemistries. Cruiser and Poncho at the 250 (.25 mg AI/seed) rate are the most common base options available for corn. These insecticides are a good foundation; however, do not expect these treatments to give you extended protection from all below ground pests. If sugarcane beetles have been a problem in the past, Cruiser at the 250 or 500 rate will not provide adequate control; consider using Poncho at the 500 rate with 1250 providing better protection. None of these products provide adequate control of cutworms. Each company offers treatments that provide differing levels of early season insect protection, outlined below are some options available to producers with regards to insecticide seed treatments.
Pioneer’s base insecticide seed treatment package consists of Cruiser 250 with Poncho/Votivo 1250 available upon request. Votivo is a biological agent that protects against nematodes.
Monsanto’s products including corn, soybeans and cotton fall under the Acceleron treatment umbrella. Dekalb corn seed comes standard with Poncho 250. Producers also have the option to upgrade to Poncho/Votivo, with Poncho applied at the 500 rate.
Agrisure, Golden Harvest and Garst have a base package with a fungicide and Cruiser 250. Avicta complete corn is also available; this includes Cruiser 500, fungicide, and nematode protection.
Another option is to buy the minimum insecticide treatment available, and have a dealer treat the seed downstream.
Avipel was re-issued a section 18 for field and sweet corn seed in Louisiana. The exemption is effective from February 24, 2012 through February 24, 2013. Avipel can only be applied at the dealer and is used as a humane bird repellent.
It is important to note that below ground Bt traits available for western corn rootworm will not work on our strain of root worm in Louisiana. Look at using in-furrow applications of Counter (organophosphate) or Force (pyrethroid) to help keep rootworms under control. If an ALS herbicide was used in burndown applications or is anticipated, organophosphate insecticides should not be used.
Insecticide seed treatments are a valuable tool that allows producers a head start on early season protection from a variety of pests. Minimizing damage below ground will help get this year’s corn crop off to a promising start.
From: Daniel Stephenson, Ph.D (Weed Scientist), Sebe Brown (Extension Entomologist) and John Kruse, Ph.D. (Cotton and Feedgrain Specialist)
Historically, many corn producers in Louisiana desire to plant corn in February. LSU AgCenter weed scientists and entomologists suggest burndown applications occur 4 to 6 weeks prior to planting to prevent competition from weeds and to remove vegetation that may be infested with insect pests – collectively known as “breaking the green bridge”.
Fields intended for corn should have already received a burndown application; however, weather conditions during January and early February may have prevented herbicide applications. As an example, 14.5 inches of rain were recorded at the Dean Lee Research and Extension Center in Alexandria since January 1.
The wet fields prevented ground application of burndown herbicides. Also, there were only a few days since January 1 that an airplane was able to make these applications due to wind conditions. As a consequence, Louisiana producers may be faced with weedy fields that are intended for corn.
A failure to “start clean” can greatly influence corn yields. Data have shown that corn determines its leaf orientation very soon after emergence. Leaf orientation perpendicular to the planted row is desired for maximum light interception, which influences growth and yield potential. If a spiking corn plant perceives any competition from an adjacent winter weed, the leaf orientation will be altered, thus potentially reducing that corn plant’s ability to intercept enough light for maximum yield. Therefore, planting into a weed-free field is very important.
Focus on Weed Control
Traditionally, a burndown application of glyphosate plus 2,4-D has been the standard protocol. This treatment usually provides good to excellent control of many winter/spring annual weeds common in Louisiana fields.
When applied 4 to 6 weeks prior to planting, a producer has time to evaluate the efficacy of glyphosate plus 2,4-D and decide if an additional herbicide treatment is needed prior to planting. If a producer is prevented from applying the burndown application in a timely manner, then weed competition and insect pressure may be an issue for emerging corn. Henbit in particular may be a refuge for cutworms and spider mites.
If a field scheduled for corn has received a burndown application, then these fields need to be evaluated to determine if corn will be planted into a “clean” field.
If the weather has prevented a burndown application and a producer intends to plant corn within the next few weeks, several factors must be considered.
The first issue is the 2,4-D plant-back restriction, which is 7 days for corn. If you are within this window, then you should not apply 2,4-D, to prevent herbicide injury to the corn. Second, maximum efficacy of glyphosate will not be observed until 21 to 28 days after application, so glyphosate applied 7 to 10 days before planting may not provide acceptable weed control and may allow insect populations to survive.
If a producer is within 7 to 14 days of planting corn, he/she should consider the following burndown treatments:
- Gramoxone SL at 1.5 qt/A plus atrazine at 1 lb ai/A plus 0.25% v/v nonionic surfactant.
- Gramoxone SL at 1 qt/A plus Leadoff at 1.5 oz/A plus 0.25% v/v nonionic surfactant.
Gramoxone SL will provide control of existing weeds, but coverage is essential. Therefore, a minimum of 12 gallons of water per acre and flat-fan nozzles should be utilized to maximize coverage. Also, Gramoxone SL efficacy can be increased when the air temperature is high and cloud cover is minimal.
Atrazine or Leadoff will assist Gramoxone SL with control by providing residual activity on winter/spring weeds during the first few weeks after corn emergence – if beds are not disturbed at planting. However, if an organophosphate insecticide will be applied in-furrow when planting corn, then Leadoff cannot be applied or injury will occur.
Focus on Insect Control
At-plant bands or post-emergence pyrethroid applications can be used to control cutworms; however, the infestation needs to be detected early to minimize stand loss. Moist soils will help incorporate the application to improve efficacy on any cutworms that may be located below the surface.
Foliar insecticide applications can be applied in bands behind the planter in reduced tillage fields. At planting soil insecticides such as Lorsban 15G can be t-banded with corn to help control cutworms pre-emergence. Lorsban should not be planted in furrow due to possible phytotoxicity. It is important to note that the use of ALS inhibiting herbicides with organophosphates such as Counter and Lorsban have the ability to cause significant crop injury.
If producers used Leadoff in their burn down strategy then Counter should not be used at all, to prevent any negative effects between the two chemicals. Lorsban has greater crop safety than Counter when used in conjunction with ALS inhibiting herbicides.
Force 3G can also be used at plant to help protect against cutworms. Force 3G is a pyrethroid insecticide and the ALS interaction is not a factor. Counter is not effective for control of cutworms but useful for rootworms.
Planting corn into a weed-free field is a must to maximize yield. Regardless of when you apply a burndown treatment, a producer must strive to “start clean”.