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Specialist Speaking print email

Some seed treatments target grape colaspis.

Specialists Speaking at this time last year was devoted to discussing the changes in insect control in rice over the past 25 or 30 years with emphasis on the new seed treatments. This article is in some ways a continuation of that discussion. Dermacor X-100 and CruiserMaxx had full federal labels in place last year and were used extensively. Valent just received an Experimental Use Permit (EUP) for the use of NipsIt INSIDE to control rice water weevil (RWW) and grape colaspis in rice.

All three of these insecticides are labeled for use only on dry-seeded rice and only can be applied by approved seed treaters; however, there are several differences between these materials, ranging from pest spectrum to application rates. The insecticides in CruiserMaxx and NipsIt INSIDE are both neonicotinoids, thus would be expected to have activity against the same pests. At this writing, NipsIt is only labeled to control RWW and grape colaspis, while CruiserMaxx targets chinch bugs and thrips in addition to RWW and grape colaspis.

Included with the insecticidal activity of CruiserMaxx is a packaged mixture of the insecticide thiomethoxam and three fungicides – fludioxonil (Maxim), mefenoxam (Apron) and azoxystrobin (Dynasty). The Maxim component is intended to control Rhizoctonia and Fusarium. Apron aims at Pythium, and Dynasty is directed at early season Rhizoctonia, Pythium and Pyricularia. All of these are pathogens capable of causing seedling diseases. Some commercial seed sources already have seeds treated with these same fungicides.

When used according to the label, they do not exceed use rates, but the duplication may not be necessary.Use of Cruiser rather than CruiserMaxx solves that problem.

Because NipsIt INSIDE is under an EUP, it will only be allowed to be used on 5,000 acres in Louisiana in 2011. This type of label is intended to allow the industry to get a good look at it in the field and compare it to results obtained in small plot replicated research.

Both CruiserMaxx and NipsIt INSIDE labels prescribe a specific amount of product per 100 pounds of seed. One consequence of this is that planting rate affects the amount of active ingredient applied per acre. This is different from the way we recommend most agricultural crop protection chemicals where the rate per acre remains fairly constant. For example, the recommended application rate of Cruiser Maxx is 7.0 ounces of product per 100 pounds of seed. If the planting rate is 100 pounds per acre, the product rate is 7.0 ounces per acre.

But if the planting rate is 25 pounds per acre, the product rate becomes 1.75 ounces per acre.

This brings into question efficacy at low seeding rates. In Dr. Natalie Hummel’s on-farm demonstrations last year, core samples revealed higher RWW larval numbers at lower seeding rates, which confirmed the observations of Dr. Mike Stout in his small plots on the experiment station. Whether these differences are significant economically remains in question. These demonstrations only involved Cruiser Maxx because NipsIt INSIDE was not yet available.

Dermacor X-100 maintains a relatively constant application rate per acre by varying the amount used per 100 pounds of seed. The label has tables showing a range of active ingredient between 0.06 and 0.08 pounds of active ingredient per acre. A second table shows the amount of material to be applied per specific amount of seed to maintain this rate range. Because the treatment rate is relatively constant, per-acre planting rate had little impact on core counts in the same studies conducted by Drs. Hummel and Stout.


Sustaining the value of Clearfield

Clearfield rice continues to gain momentum in the market across the Mid-South as better variety selections have become available. Effective barnyardgrass control, red rice control and ease of use has also helped to improve the popularity of Clearfield rice. In 2010, Clearfield rice accounted for more than 60 percent of the rice acreage in Arkansas, and the anticipation is that that number will increase during 2011.

Many growers also are looking at Clearfield rice as an option simply for “self-defense.” Because of misapplications and drift problems related to nearby Clearfield rice, conventional rice can be a challenge to grow and becomes costly for recovery efforts when mistakes are made.

One problem that has surfaced as a result of increased Clearfield acreage is the development of barnyardgrass resistance to Newpath. When this resistance develops, it is also resistant to essentially all ALS-type herbicides. For rice, this includes Newpath, Beyond, Regiment, Grasp, Londax and League. We have also documented some fields that have barnyardgrass that is not only resistant to the ALS herbicides but also to propanil and Facet. With the three-way resistance, the grower is very limited in his grass control program. For pre-emergence control, he must depend on Command, Prowl and/or Bolero. For post-emergence control, he is limited to Ricestar and Clincher.

Options are available to assist growers in reducing the risk of developing resistance to Newpath. The first thing is to follow the stewardship program. Crop rotation, particularly when alternative herbicide chemistries are incorporated, is essential. Ideally, Clearfield rice should be produced no more than two years in a four-year period. In most of the cases where Newpath resistance has been confirmed, Clearfield rice has been grown continuously for several years.

In addition to crop rotation, the herbicide selection should be considered. Use of pre-emergence herbicides such as Command, Prowl or Bolero provide alternative herbicide classes that have different modes of action. If resistant grass is present, the alternative modes of action helps control those plants. Another step that can help reduce resistance is to prevent escapes. I know that roguing is not likely, but it would be worth the cost of spot treating. Many times escapes are present near treelines or under power lines because aerial application is challenged. Not controlling escapes in these areas led to higher potential for resistance. Using ground equipment can often facilitate treating these escapes.

Preventing herbicide resistance requires a concerted effort. Crop rotation, controlling escapes and incorporation of herbicides with different modes of action are the three main spokes of the wheel that will allow sustained value of Clearfield rice.


Rotation is key

Herbicide resistance continues to be an ongoing battle, not only in rice, but in many other crops as well. Producers need to look at resistance management as a whole-farm approach. Also, if you consistently use the same weed control program, you probably need to look at changing it up because you are setting yourself up for a resistance problem. For example, look at the repeated use of glyphosate and how quickly resistance evolved in that weed control program.

Rotation is a key to help prevent herbicide resistance. Rotation needs to be incorporated across the whole farm at three different levels: Herbicide rotation within each crop, crop rotation in general and herbicide rotation across all crops.

Just because you switch herbicide products does not necessarily mean that you switched herbicide modes of action. Over the last couple of years more pre-mix products have been introduced into the marketplace. This is basically taking old herbicide products and combining them to make a new herbicide product. This is not a bad thing for rice producers, but it sometimes gives a false sense of practicing herbicide rotation.

Crop rotation has always been a sound practice in row-crop production, but it will especially help prevent herbicide resistance issues. Crop rotation will allow you to use a multitude of chemistries that are available other than just specific ones within a given crop. This gives way to my third point – rotate herbicide chemistries across all crops. Repeated use of the same mode of action in both rice and soybeans increases the possibility of herbicide resistance in both crops for that mode of action. When rotating to another crop, other than rice, use modes of action that are not labeled for rice. Examples would include atrazine in corn and metolachlor in soybeans.

Lastly, the amount of new herbicides and herbicide modes of action under development in rice is essentially zero. As a result, we will have to manage weed control with the products that are currently labeled for use in rice. Rotation is a critical component in keeping the current technology available and effective for rice weed control now and in the immediate future.


Recognize the enemy

This month’s topic – early season insect management – is right up my alley! Fortunately, our farmers have an array of tools and management options to control early season insect pests of rice. Regardless of arthropod pest, scouting is the first line of defense for early season pest control. If you don’t know pests are present, how are you going to deal with them?

So, get out your hand lens, put on your field boots and thoroughly inspect your fields as soon as rice emerges. Continue to inspect all the way until your fields are drained! Early season insect pests in Texas include chinch bug, aphids, thrips, fall armyworm and South American rice miner.

Adult chinch bugs are small, black and have an “X” pattern of white on the top of their bodies. The nymphs are smaller and orange. These pests have piercing-sucking mouthparts, which they insert in the stem and roots of plants. They withdraw fluids from the young plants, which can cause stunting, rosetting, yellowing and stand loss. During the heat of the day, chinch bugs can be found in the cracks and crevices of soil or near the crown and roots of plants. The treatment threshold is one adult chinch bug per two rice plants. Timely flushing can control these pests, but levee rice remains vulnerable.

The seed treatment CruiserMaxx gives good control of chinch bugs. Another seed treatment, NipsIt INSIDE, also gives good control. NipsIt INSIDE received an Experimental Use Permit for the 2011 season and can be applied to a maximum of 10,000 rice acres in Texas this year. These seed treatments will control chinch bugs that are attacking both levee and paddy rice. Pyrethroids also will control chinch bugs, but timely application is essential. Apply the pyrethroids in the early morning or late evening when chinch bugs are more apt to be feeding above ground. Texas data also show herbicide injury can exacerbate chinch bug damage.

Aphids attacking seedling rice include bird cherry oat aphid, yellow sugarcane aphid and rice root aphid. Aphids are soft-bodied, globular-shaped and move slowly. Adults have transparent wings that are held roof-like over the body. Aphids are most often found on foliage and stems, but the rice root aphid can also be found in colonies on rice roots. Like chinch bugs, aphids have piercing-sucking mouthparts that they use to extract fluids from young rice.

Damage symptoms are stunting and yellowing of rice; however, the yellow sugarcane aphid can also cause reddening of foliage. This aphid species is bright lemon-colored and can cause stand loss. A toxin is thought to be injected into the plant when this aphid feeds.

Aphids reproduce quickly and can build to high numbers in a short period of time. Many aphids are parthenogenetic, which means the females can lay viable eggs without mating. Also, some aphids can give birth to living young – they skip the egg stage!

If you see lady bird beetles in your fields, you can almost bet you have an aphid infestation. Adult and larval lady bird beetles are voracious predators of aphids. The larvae of lady bird beetles are predominately black and elongated. Another predator is lacewing larvae that are shaped like lady bird beetle larvae, but are brownish, possess sickle-like mandibles and look somewhat like miniature alligators! Control options are similar to those employed to manage chinch bugs. Yes, CruiserMaxx and NipsIt INSIDE control aphids. Insecticides containing carbaryl are not effective against aphids. Currently, no treatment thresholds exist for aphids, but if widespread damage is evident and aphids are present, it’s probably past time for application of effective control options.

Thrips are very small insects with fringed wings (you must use a hand lens to see). As a side note, the singular and plural spelling of this insect is “thrips.” Thrips usually can be found on seedling rice between the junction of the leaf blade and the sheath. Damage is caused when thrips rasp (they have rasping-sucking mouthparts) the young, tender tissue, which can result in deformed leaves and stunting. Thrips excrement, which looks like small grains of black pepper, can be observed on affected foliage. Damaged leaves take on a silvery appearance due to the rasping activity of the thrips. I have never observed a field requiring treatment for thrips, but timely flushing will reduce populations. Again, CruiserMaxx and NipsIt INSIDE will control this pest.

Fall armyworms can attack young rice and defoliate entire fields quickly. The adult fall armyworm is a moth that is active at night. The female lays eggs in a mass on rice foliage. Eggs hatch, and the larvae progress through 4-6 instars – each stage larger than the previous one. The early stages can be difficult to see, but you can readily observe foliage with linear, ragged defoliation. The larvae have a characteristic upside-down “Y” on their foreheads. Cattle egrets in fields can alert you to an infestation, but don’t assume – get out of your pickup and check!

Usually, if egrets are feeding on fall armyworm larvae in your field, your rice has already suffered unacceptable damage. Pieces of cut leaves next to the windward side of levees or around water boxes also can indicate infestations. Timely flushing can reduce populations. The seed treatment Dermacor X-100 is very effective against fall armyworms. Pyrethroids also are effective.

The South American rice miner can cause injury to seedling rice, but I have not observed populations in Texas requiring treatment. However, Louisiana has experienced some severe stand losses in the past. The adult of this pest is a small, grey fly that lays a single egg – very white – on rice foliage. The egg hatches, and the small larva moves to the junction of the leaf blade and sheath where it mines the tender tissue. This feeding can result in stand loss, which is usually associated with late-planted rice. The seed treatment Dermacor X-100 controls this pest. All the above pests can be controlled culturally or chemically, but you farmers and crop consultants need to be vigilant in your efforts to detect early infestations before damage occurs. I wish ya’ll a very productive season, and, if you have questions, please contact me (409-658-2186; moway@aesrg.tamu.edu).

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