Addressing Early Season Pests

ARIZONA | Randy Norton

As we enter the early stages of crop development this season, we will begin to see the appearance of the first pinhead squares. The crop will be quickly progressing from a vegetative stage to a reproductive stage. The occurrence of the first fruiting branch, or transition to reproductive development, should occur at approximately mainstem node six to eight. This is dictated primarily by crop genetics but can be influenced by environment.  

Early season insect pressure and feeding by thrips or flea beetle can result in loss of apical dominance, split terminals, forked plants and a delay in the onset of fruiting. New traits released for full commercial, unrestricted planting can provide a significant level of protection against early season insect damage, particularly by thrips. The new ThryvOn technology is present in several commercially available varieties that can be planted this season with no restrictions. Protecting the young, developing plants from any factors that can delay fruiting is essential in optimizing production and efficiency.  

Over the past several years, we have seen an increase in planted acreage of non-Bt cotton varieties. Some of this has been as a result of the increased Pima acreage, but there have also been additional varieties that have been planted in limited acreage that are conventional or non-Bt varieties. In some areas of the state, we have experienced increased bollworm pressure in many of these non-Bt fields. Monitoring for bollworm moth flights and egg lay is critical to managing this pest effectively. Having a pest control advisor scouting your fields for these pests is important in maintaining and protecting the developing fruit load on young cotton plants.  

For more information on these topics and other cotton-production-related topics, visit our website at extension.arizona.edu/crops-soils. rnorton@cals.arizona.edu

TEXAS | Ben McKnight

As I write this the first week of April, nearly all the cotton acres in the Lower Rio Grande Valley have been planted. Just north of the LRGV in the Coastal Bend region, many growers that didn’t have good soil moisture to plant into are waiting for conditions to improve prior to the April 15 insurance cutoff date. Conditions have been dry lately in the Upper Gulf Coast region, and approximately 50% of the cotton acres there have been planted as of early April. By the time you are reading this in early May, planting in the Winter Garden and Blackland Prairie regions will be well underway, if not close to wrapping up. As good chances of precipitation have recently shown up in the extended weather forecast, it appears that the dry weather pattern that has been lingering across much of central and southern Texas for some time may be easing up a bit. 

While rainfall is greatly needed for replenishing soil moisture and getting the dryland crop out of the ground, it also initiates the life cycle of cotton pests that are found in every production field in the state of Texas. Weed pressure early in the season can lead to considerable yield consequences if not addressed in a timely manner. I am a big fan of being aggressive and early with weed control efforts, especially in fields with particularly troublesome weed species like pigweeds and common sunflower. 

Residual herbicide products can offer substantial value to the overall weed management program if used according to the label. Many of the residual products need to be “activated” with rainfall or irrigation. It’s always a good idea to familiarize yourself with the product label and the specific requirements each residual product needs to provide the highest level of activity and return value to our overall management programs. 

Control of highly competitive species like pigweeds, while they are still a germinating seed or young seedling, greatly reduces the pressure we put on our postemergence herbicide programs. Tall waterhemp and Palmer amaranth have extremely rapid growth rates under the right environmental conditions and can quickly get beyond a size where reasonable control can be expected with a postemergence product. Overlaying residual herbicides through tank-mixing with our postemergence applications can offer extended control of these rapidly growing weed pests further into the growing season and help get us across the finish line with a clean field. bmcknight@tamu.edu 

MISSOURI | Bradley Wilson

We are still a few weeks shy of planting in Missouri; however, with temperatures in the 70s and 80s, it has been tempting to get the planter out and drop cottonseed in the hoppers. Several early season pests can impact cotton growth following planting. 

Thrips are major early season insect pests in cotton through the four-leaf growth stage. Management options of thrips include an in-furrow insecticide or foliar insecticide application at the one-to-two-leaf growth stage. Severe storms causing sandblasting to cotton following emergence can cause symptoms like thrips damage. It is important to confirm thrips are present and above threshold prior to making a foliar insecticide application. 

Several soil-borne diseases can impact cotton emergence during our planting window. Planting into favorable soil conditions with a warm, five-day outlook can reduce seedling disease incidence. When planting on poorly drained soils or in unfavorable conditions, in-furrow fungicide applications can provide greater protection against organisms that can cause seedling disease. 

Nematodes are a yearlong pest, but control options are limited to at-planting management options. Typically, root-knot nematodes are the dominant species in Missouri fields. Management options include cotton nematicide seed treatments, in-furrow nematicides and resistant varieties. Cotton seed treatments do not provide lasting control in fields with heavy infestations, and in-furrow nematicide applications will provide greater control. brwilson@missouri.edu

TENNESSEE | Tyson Raper

In March, our planned acreage for 2023 was heavy soybeans with a reduction in corn and cotton, relative to 2022. As I write this April 5, we don’t have much corn planted, and it looks like we may not get much done before it rains again. Given our forecast holds, some will likely have to make the decision to plant late corn or change to soybeans or cotton.  

I’ve outlined several strategies to reduce input costs in the cotton production system over the past several months — most significantly reducing seeding rates to target about two plants per row foot and reducing total applied nitrogen. The benefits provided by these two strategies accumulate over time.  

First, with less plant-to-plant competition and less N driving plant height, plant stature will be shorter and light penetration into the canopy will be greater. This will result in less plant growth regulator required and more first position fruit retention lower on the plant. Penetration of insecticides will be better, and because the fruiting window will be shifted earlier in the season, less overall insecticide use will be required. Defoliation will be easier with less vegetation and a more compact fruiting zone. By emphasizing earliness, these decisions will also allow you to reach maturity faster. 

Cotton may not look as enticing in 2023 as it did in 2022, but sound agronomic management decisions like the two I’ve mentioned above will help push the bottom line of the cotton budget in the right direction. traper@utk.edu

VIRGINIA | Hunter Frame

Planting intentions for cotton in Virginia are expected to be slightly lower in 2023 than in 2022. Luckily, most fertilizer and input prices have fallen slightly as producers gear up for planting in May. Currently, preplant/at-planting soil fertility recommendations are 25% to 30% of total applied nitrogen, phosphorus and potassium applied at soil test recommendations, and five to 10 pounds of sulfur in preplant/starter blend with nitrogen. 

One new planting hurdle producers may be facing is establishing cotton into high biomass cover crops. This can be trickier than planting corn or soybeans, and producers need to keep an eye on seed placement (specifically depth) when dealing with high-biomass cover crops. 

Another early season management factor for Virginia growers is thrips control. I encourage Virginia producers to contact Dr. Sean Malone for up-to-date recommendations for early season management of thrips. Also, the annual Virginia Cotton Growers’ Field day will be held August 18, 2023, so go ahead and put it on your calendars! whframe@vt.edu

NORTH CAROLINA | Guy Collins

Depending on prevailing weather, May triggers cotton planting in North Carolina. Given that our planting window and insurance deadlines are rather narrow compared to other states, there is always an eagerness to get started. This winter and spring has brought some abnormally warm spells throughout. When we have a few days in a row of nice weather, folks get antsy and eager to plant, occasionally with little consideration given to the next week’s weather or longer-term forecasts. 

Naturally, no one planted cotton in February despite the fact that temperatures were essentially ideal for a few short spells during that time. However, it becomes much more tempting when nice weather occurs as the typical planting season approaches. 

Conditions during the first five days after planting are critical for stand establishment and seedling vigor, with the first two to three days during that window being the most critical. In addition, keep in mind how long it takes for cotton to fully emerge. Under the best of conditions, cotton can emerge in four to five days, although that is rare. More commonly, when experiencing good conditions, emergence in six to eight days can be expected, which is prolonged to 10 to 14 days when planting in cooler or marginal conditions. Therefore, even though weather may be nice for a day or two, we should be conscientious of the likely weather forecast beyond that.  

The North Carolina State University Cotton Planting Conditions Calculator (https://products.climate.ncsu.edu/ag/cotton-planting/) provides a five-day rating for planting conditions, applicable to the day you use the calculator and the day following. This covers the most critical window for emergence, however it may behoove us, during the early part of our typical planting window, to watch the 10-to-14 day forecast to understand what may lie ahead. If those longer-term forecasts suggest poor conditions are to be expected, we can often avoid prolonging emergence or even replanting by waiting until better conditions arrive.  This really only applies to the early portion of our planting window (late April to early May).  

Depending on a grower’s acreage and equipment/labor capacity, we often get to a point usually around May 10-15 where we have to plant regardless of conditions if we are going to meet insurance deadlines. guy_collins@ncsu.edu

GEORGIA | Camp Hand

As I write this April 5, the weather is beautiful in Tifton, and we are entering the planting window here in Georgia. I am sure by the time you are reading this, there will be a good bit of cotton up across the state. Of course, one of the biggest struggles in cotton production each year is getting a stand. But, at and after planting, we need to be mindful of early season pests. 

Many growers are scrutinizing inputs right now and looking for where to cut. In many cases, cutting up front can cause a lot of heartburn on the back end. Three early season pests I would keep at the forefront of my mind at planting would be nematodes, thrips and weeds. 

For nematodes, planting a resistant variety or using the appropriate nematicide is a decision to be made at planting, and as Dr. Bob Kemerait preaches, once the furrow is closed, there is no going back. Of course, the only way to make a good decision on nematode management is to know what’s out there (and the only way to know what’s out there is to pull samples, hopefully last fall), and that will inform which management strategy will best suit your farm. 

With respect to thrips, they are the most predictable insect pest of cotton. Planting before May 10 in Georgia will generally put you at a higher risk for heavy thrips pressure, and an at-plant insecticide will be necessary (unless you are planting a ThryvOn variety) because a seed treatment by itself isn’t going to cut it. 

Lastly, one of the best things you can do in a weed management program, regardless of the weed you are targeting, is to utilize at-plant residual herbicides. These will help the crop get ahead of any problematic weeds in your fields and delay resistance to our limited arsenal of postemergence products. Using two effective mechanisms of action for your most problematic weed (likely Palmer amaranth) is a must. 

As always, your local UGA county Extension agent and specialists are here to help! Reach out if you have any questions. camphand@uga.edu 

ALABAMA | Steve M. Brown

New technology creates headlines. Deservedly so. ThryvOn, the new thrips and plant bug management trait from Bayer, has received considerable attention in recent months. 

Still, less than 10% of most areas will likely be planted in ThryvOn, so here are a few reminders about the other 90% — fields planted in non-ThryvOn cotton.

→ Don’t plant seed without some form of thrips protection, either in the furrow or on the seed.

→ Seed treatments provide less thrips control than other measures such as in-furrow applications of imidacloprid (liquid sprays) or Ag Logic (granules). Ag Logic (aldicarb) is the “gold standard.”

→ Take advantage of the Thrips Infestation Predictor for Cotton to forecast expected thrips pressure for your area for a given planting window. Use the model to guide the aggressiveness of at-plant and early foliar insecticide programs.

→ If heavy thrips pressure is expected and at-plant control is limited to seed treatments, you may need an almost-automatic foliar spray at the first true leaf.

→ On young cotton, look for thrips and the early signs of damage in the plant terminal. Observed damage on unfolded true leaves indicates thrips have already been feeding in the terminal and on emerging tissue … and that ideally, foliar sprays should have been initiated a few days earlier.

→ Thrips injury is often compounded when crop growth is slowed by stress from cooler temperatures, crusted soils and/or herbicide injury. 

→ Conversely, aggressive early growth, which is consistent with warm weather, good moisture, and strong seedling vigor often minimizes the effects of thrips.

→ Presence of immature thrips, those that appear yellowish and smaller than the adults, suggests that at-plant control measures have diminished considerably and that foliar sprays may be needed, depending upon plant growth stage and conditions.

→ Once plants reach the fourth or fifth true leaf, cotton is often beyond the window of significant damage from thrips — but not always.

→ Multiple foliar applications of acephate for thrips sometimes contribute to later problems with spider mites. A single application may do the same, especially if treatments are made in the later stages of the thrips control window. cottonbrown@auburn.edu

MISSISSIPPI | Brian Pieralisi

Cotton acres in Mississippi are expected to decrease 25% compared to 2022. With a decrease in both acres and cotton prices, managing early season pests is paramount to avoid maturity delays and reap a successful harvest. Planting season went exceptionally well in Mississippi last year but was later stressed by a two-to-three-month drought. As I write this, spring is ahead of schedule due to the warm/hot weather; thus, conditions are lining up for early planting dates. However, a cold snap is never out of the question until after the first two weeks of May. Growers should focus on management tactics within their control and take advantage of any favorable planting opportunities.

Thrips are the primary early season pest affecting Mississippi cotton. Over the past several years, thrips pressure has been unusually high, causing multiple applications in some cases. This can likely be attributed to slow-growing cotton met with environmental conditions favorable for this pest. Typically, by the three-to-four-leaf stage, cotton plants are past the most susceptible stage for economic injury or delays in maturity. However, a sound management plan is in order to mitigate injuries from Thrips. ThryvOn cotton will compromise 10% to 15% of our acres. Currently, ThryvOn cotton effectively manages thrips, allowing for rapid progression through the developmental stages under favorable growing conditions and adequate heat unit accumulation. 

Early season thrips management typically consists of: imidacloprid-treated seed or in-furrow treatments followed by foliar applications. In-furrow treatments of 1.1 pounds of acephate or 8 ounces of imidacloprid should be directed on or below the seed for most-effective control. Under high reniform nematode populations, 3.5 pounds to 5 pounds of aldicarb is another option. Most current cotton varieties are pretreated with recommended fungicides; however, using in-furrow insecticides increases susceptibility to cotton seedling diseases. So, be sure to plant seeds treated with a recommended fungicide.

Lastly, most cotton grown in Mississippi is conventionally tilled and cutworms are not an issue. However, with an increase in both cover-cropped and no-till acres, cutworms could establish on existing vegetation.  Cover crops should be terminated at least three weeks prior to planting to avoid risks associated with stand reduction.  If vegetation is not terminated three weeks prior to planting, a pyrethroid should be used at planting, which will protect early season cotton seedlings from stand reductions. bkp4@msstate.edu

LOUISIANA | Matt Foster

According to the USDA National Agricultural Statistics Service, cotton acreage intentions in Louisiana are at 130,000 acres, down 33% from the 195,000 acres planted last year. As I write this April 4, substantial rainfall is predicted for some cotton producing areas in the state as the optimal planting window approaches. Cotton planting should begin soon depending on field conditions. 

After crop emergence, producers should concentrate on managing the cotton plant from the first- through fifth-leaf stage. Reaching the fifth true leaf stage with minimal damage from thrips is a key factor in producing good cotton yields. Seed treatments for controlling early season insect pests play a valuable role in getting the cotton plant off to a rapid start. Depending on environmental conditions, seed treatments may last anywhere from 14 to 28 days. Oftentimes, under cool spring temperatures, reaching the fifth true leaf stage is delayed and seed treatments may lose their effectiveness. Under these conditions, foliar sprays may be needed. 

Also, once stands are established, nitrogen applications are made for the upcoming season. Recommended nitrogen rates are 60 to 90 pounds per acre for coarse-textured soils and 90 to 120 pounds per acre for finer-textured soils. The lower recommended rates should be used on fields that are following soybean, corn, legume cover crops or fields with a history of excessive stalk growth. Caution should be used to not apply excess nitrogen that can produce very tall and rank cotton. Increased vegetative growth will hinder reproductive growth and, ultimately, yield. To limit excessive growth, producers will have to rely heavily on mepiquat chloride applications.  

Best management practices suggest making split applications of nitrogen on sandy soils with high leaching potential or soils with a high saturation potential because of denitrification losses. For split nitrogen applications, one-third to one-half should be applied at planting with the remainder applied by early bloom at the latest. Best of luck during the upcoming season. mfoster@agcenter.lsu.edu