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Posts Tagged ‘hybrid rice’

I didn’t set out yesterday knowing the day would play out like it did, but in honor of Cinco de Mayo, we wound up with five insects to discuss.  All of which we found in rice fields on Cinco de Mayo.

Numero Uno

I’ve continued to get a lot of calls about some strange injury in rice – chewing at the base of plants, digging/tunnels in the soil, and declining stands. After lots of head scratching, research, and some conversations in the halls of the “ivory tower” with my colleagues, we finally started to put it together. All signs pointed to sugarcane beetle. A new Ph.D. student, Karen Nix, and I headed to the field in Jefferson-Davis Parish to scout with County Agent Barrett Courville and Crop Consultant Benet Augustin. I told Benet he’s going to get a prize for finding the most odd insects this season. I’m certain he’d rather do without that recognition…

The first thing Benet had described in this field was a reduction in stand in hybrid rice treated with CruiserMaxx.  Cruiser had been used because of historical problems with chinch bugs in this particular rice field.

Stand loss in a hybrid rice field treated with CruiserMaxx - injury caused by sugarcane beetle adults feeding on crown of plant.

As we walked into the field, it was not difficult to find plants with soil disturbed at the base of the plant.

Soil disturbed at base of plant by a sugarcane beetle adult digging.

We dug around the base of the plant and in many places were able to quickly locate a large black beetle.

Sugarcane beetle adult with injured rice plant.

The sugarcane beetles are injuring the rice by chewing at the soil line in the crown of the plant. Some of the plants are dead or dying, while others may still recover by tillering.

Injury caused by a sugarcane beetle chewing on the base of the plant.

I called Dr. Tara Smith (Sweet Potato Extension Specialist and Entomologist) to learn more about sugarcane beetle biology. Tara studied this insect for her dissertation research. The symptoms we are seeing in rice are very similar to what you will find in field corn (where the sugarcane beetle is causing some injury in Arkansas this season). I discussed treatment options with Tara. She confirmed that Thiomethoxam (the active ingredient in CruiserMaxx) does not have good activity against this insect.

Treatment recommendations are tied to the biology and behavior of the insect. Sugarcane beetles overwinter as adults, and then move into field crops and attack plants at the soil line. During this time of year, they will be flying, mating and laying eggs. Flying usually occurs from dusk to 10 pm. Thus, we advised treating with a pyrethroid sometime around dusk to increase the odds of insecticide coming into contact with the beetles – a spray applied during the day would probably be less effective because the beetles are down in the soil. Alternatively, bringing a permanent flood as soon as possible should also prevent further injury. In this field, the rice is not ready for a permanent flood.

I’ve never observed these insects in rice, and apparently, they are a rare problem. Is anybody else finding these in rice fields?

Numero dos

We moved on to another field after we confirmed the sugarcane beetle problem. This field was suspected to be infested with colaspis larvae. This was a field of hybrid rice which did not have an insecticide seed treatment applied. It was drilled into a stale-seedbed, which was planted in soybeans in 2010. Sure enough, we found a severe infestation of colaspis larvae that was reducing the stand.

Stand loss caused by colaspis larvae feeding on the roots of rice plants.

It was not difficult to find colaspis feeding in the soil anywhere from 1/2 inch to 3 inches below the soil line.

Colaspis larva on root of rice plant.

It’s easy to see how these little larva can inflict injury on the roots of a rice plant when you look at the large size of their chewing mouthparts (mandibles).

Head-on view of a colaspis larva - the dark brown structures are the mandibles which are used to chew up plant material.

We advised applying a permanent flood as soon as possible. Also recommended using a pyrethroid to prevent injury from rice water weevils – weevil scarring on the leaves was common in the field. The pyrethoid will not have a significant effect on the colaspis larvae, but the larvae will stop injuring the rice after application of permanent flood.
 
Numero trece y quatro 
 
While scouting the colaspis infested field we found a couple of other insects feeding on the rice. This included chinch bugs and a mystery insect.

Chinch bug nymph feeding at base of a rice seedling. This injury can cause stunting and plant death.

Application of a permanent flood will also stop the injury from chinch bugs, because they will no longer be able to feed on the growing point of the plant once it is protected by the flood water.
Mystery insect on roots of rice plant – note the ants that are “tending” them.
This was the first time I’d come across these creatures. These mystery insects looked like some type of plant feeder – possibly a homopteran. It didn’t look like they were causing any injury, but it was a curiousity that I couldn’t miss photographing. Unfortunately, my pictures were a little blurry. I’m working on an identification today.
  
Numero cinco
 
The last field we scouted was a field of hybrid rice that was water-seeded. The stand was marginal and the rice was dying. We suspect that a variety of factors may have contributed to the plant injury, one being excessive rice water weevil adult scarring. The field did not have any insecticide seed treatment (because it was water-seeded). It is bordered by a crawfish field, so options are limited. We will see how it progresses.

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 I lived in Texas for a couple of years before I moved over to Louisiana. Lately it seems that all my field calls have been pulling me back in that direction, but I haven’t managed to have an bbq yet. Although I did have a delicious BLT with egg for breakfast. I never would have thought of that combination – Cajuns truly are the most creative and talented cooks I have ever known.
 
Today we started off with the Vermilion Parish Rice Grower’s mtg at Suire’s Grocery before heading out to scout rice fields in Calcasieu Parish. We had a great turn out at the meeting. Dr. Saichuk and I discussed observations we have made so far this season. Saichuk’s comments concentrated on herbicide drift problems, the dry conditions causing all sorts of trouble and some other general issues with some varieties. I discussed the seed treatments, trouble with chinch bugs, colaspis, and what we have going for the rice water weevil demonstration this season.
 
After the meeting we headed over to Lacassine to meet Benet Augustine. Benet had called on Thursday to report some strange problems with rice – the heart of the mother tiller was dying in young rice and the dead new leaf could be easily pulled out of the plant because it was severed at the base. There also appeared to be some chewing at the base. We tried to puzzle it out over the phone. Soon after, Dr. Saichuk and Barrett Courville visited the field and found rice levee bill bugs – an application of Karate was applied before the rain storm and we could not find any living bill bugs – actually none at all – during our scouting visit today. The lack of insects caused me to be uncertain of whether the bill bugs had been responsible for the rice injury. A few fields later we found another bill bug infestation near Iowa and caught them “red-handed” causing the same injury as Benet had observed. So that mystery was solved. Following are some pictures of the bill bugs and the associated injury they can cause to seedling rice. This was my first time collecting them in a rice field. They have caused significant stand reduction at both sites – both were treated with Dermacor X-100, and both were hybrids planted following a fallow season.
  

Bill bug injury field shot. Note the thin areas in the stand.

Bill bug stand reduction in hybrid rice.

 

Bill bug feeding injury in the leaf sheath near the base of plant (the plant is upside down in this picture).

A bill bug feeding near the base of the plant – they like to be upside down for some reason.

Here is where we observed a bill bug feeding. You can see that he has his “snout” is embedded into the leaf sheath. Bill bugs belong to the beetle family Curculionidae (weevils) and are a relative of the rice water weevil. Their chewing mouthparts are found at the end of a long “snout”. The bill bug feeding appears to be injuring the heart of the tiller, causing death of the new leaf. This explains the severed end when the dead leaf is pulled out of the leaf sheath. I saw this injury last season in Calcasieu Parish but was never able to catch the culprit.

We commonly found the bill bugs burrowed in at the soil line, or about half an inch above the soil line on the plant.

We found a pair of bill bugs mating near the soil line.

Red arrow: bill bug and yellow arrow: rice water weevil adult. Demonstrating relative size by comparison to a buck knife blade.

We recommended treating with 2 oz of Karate to prevent further injury from the bill bug. This field is particularly vulnerable because of the low seeding rate. The stand is already marginal and we hope some of the plants recover from the injury. Karate was used at another field location (as described above) and it appeared to be effective.

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

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). 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.

Healthy rice plants that are just starting to show injury, bordered by dead and dying rice plants. 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. This field was infested with all life stages of chinch bugs, ranging from nymphs to adults. 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.

Chinch bug adult at base of plant – note the black and white color pattern that gives the appearance of an hourglass. We also found mating pairs of adults.

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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This morning I admired the moon setting over University Lakes on my way into campus. Wait a minute, I was biking into campus by moonlight? Yep, a sure sign of field season – early mornings and long (but exciting) days. Today we headed down to Jefferson-Davis Parish to scout a couple of fields that were suffering from stand loss due to an unknown cause. In one location we are still trying to determine the cause. In the second field we scouted we confirmed a fairly severe colaspis infestation. We met with Farmer Kyle Fontenot, Consultant Ron Smith and Nicky Miller at the field which is located between Hathaway and Elton.
 

Kyle Fontenot, Anna, Nicky Miller, and Ron Smith. Note that Kyle and Nicky were both on their iPhones connecting with me on the blog and facebook.

 
Within a few minutes of digging we had no trouble finding many plants with colaspis larvae feeding on the roots, causing the plants to decline and eventually die.

Stand reduction in a hybrid rice field that was caused by colaspis larvae feeding on the roots of the plants.

 

We typically found the larvae on dying plants approximately 2 inches below the soil line.
A colaspis larva.
A colaspis pupa near the tip of a knife blade to give you an idea of the size.
 

 

It is worth noting the history of this particular field. In 2010 it was used as cattle pasture. To prepare the field for rice, the farmer plowed in the fall, burned the vegetation (with fire) in December/January, then plowed again, and finally plowed, shanked, and fertilized before planting. Rice was broadcast and then packed. The planting method made it even harder to determine the cause of injury because we did not observe the typical loss of plants along a drill row that we have seen in the past with colaspis infestations.

Visit this website for more information on the biology and scouting for colaspis in rice: http://www.lsuagcenter.com/en/crops_livestock/crops/rice/Insects/LSU+AgCenter+Rice+Training+Session+How+to+Scout+for+Grape+Colaspis+in+Rice.htm

This field was planted with hybrid rice seed that was treated with Apron, Maxim, Dynasty and Dermacor X-100. Dermacor has a registration for suppression of colaspis and previous research has indicated it will provide about 40% control. It is possible the injury would have been worse without the Dermacor X-100 treatment. If CruiserMaxx or NipsitInside would have been used, then we probably would not have experienced this much stand reduction. Dermacor was selected because of the history of rice water weevil pressure at the field site. It was determined that a replant was not necessary. At this point, the only option is to bring a light pin-point flood to hopefully stop the feeding of the colaspis larvae and prevent further injury of the rice.

I suspect that the colaspis problems may be more widespread. After they left this field Ron Smith called to say that they also found colaspis in another nearby field. I’ll be back down that way next week to further investigate the situation.

 

 

 
 

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I knew my phone was too quiet last week…

Today I’ve have four calls about insect problems in rice. Yesterday I ran the battery down on my phone between phone calls, e-mails 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 bugs 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.

You can click on the pictures to make them larger.

In Evangeline Parish we found a few chinch bugs feeding on the plants.

Chinch bug near base of rice plant.

 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?

Chinch bug mating pair on the soil surface.

 As I was taking pictures, they shifted position – here is a close-up.

Chinch bug mating pair.

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.  Here is a composite picture from my files for your reference – these pictures were taken in Jeff-Davis Parish a couple of years back.

 

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.

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 NipsitInside) 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.

 

Plants grown from Dermacor X-100 treated seed to the left and CruiserMaxx treated seed to the right.

Plants grown from NipsitInside treated seed to the left and Dermacor X-100 treated seed to the right.Plants grown from untreated seed (fungicide only) to the left and NipsitInside treated seed to the right.

Plants grown from Dermacor X-100 treated seed to the left and untreated seed to the right.

Plants grown from NipsitInside treated seed to the right and Dermacor X-100 treated seed to the left.

Plants grown from CruiserMaxx treated seed to the left and NipsitInside treated seed to the left.

Plants grown from untreated seed to the left and CruiserMaxx treated seed to the right.

As we walked across the field site we noticed many fire ants and also parasitoid wasps, which led us to believe there must have been some insects in the field that these predators/parasitoids were consuming.  Sure enough, after some searching we started to find aphids, thrips and chinch bugs.  None are present at levels that are causing noticeable injury in the plots, but we will certainly keep an eye on the populations.

 

Fire ants foraging in the Evangeline Parish test site field.

In this situation, the fire ants are helping us by eating some of the insects that are attacking the rice – including aphids, thrips, and possibly chinch bugs. Of course, they also took a couple of bites out of me  as I was attempting to take picture in the windy conditions at the field. 

Fire ant foraging for insects infesting a rice plant - in this case, it looked like it was searching for thrips.

 

Thrip on a datasheet after it hopped off a rice plant. The datasheet is printed in 10 pt font, so you can see the miniscule size of the thrip adult.

Thrip adult on a rice plant leaf blade - we commonly found them on the blade or in the leaf sheath area. It appeared that feeding injury was causing discoloration on the sheath, but this was not confirmed.

 

We found a few aphids on some of the plants. It is likely that populations would be higher if they were not being attacked by ladybugs.

Ladybugs were also present in the field eating the aphids.

 The herbicides had not gone out yet, they will probably go out today, and so we took a few moments to enjoy a sweet gift of nature – wild blackberries on the edge of the field.

Anna picking blackberries during lunch break – ah the sweet rewards of field work…

Tomorrow we will make some site visits in Jeff-Davis where possible colaspis injury has been reported. In the afternoon, we will head to St. Landry Parish to take stand counts at our demonstration site.

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