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August is the month when Alabama soybean producers typically make the most foliar applications of insecticides to soybeans. The primary targets of these applications are stink bugs (SB's) and caterpillars. SB's begin moving into soybean fields in significant numbers when small beans begin forming in the pods. SB's are long-lived insects that can cause a lot of damage to soybean crops. Adults can live for up to two months, while immatures take 30 days to go through five instar stages. Adults lay 30-130 eggs per egg mass, and these eggs generally hatch within five days during the summer. Thus, once the adult population becomes well established SB numbers can increase quickly. As beans within the pod get bigger they tend to suffer less damage from stink bugs. Thus the economic threshold increases from 2 per 15 sweeps across two rows prior to mid-pod fill to 3 per 15 sweeps after mid-pod fill.
This year the brown stink bug initially was the most common stink bug observed in most cotton and soybean fields. The brown stink bug is more cold tolerant than the green and southern green stink bug (SGSB). The cold winter is expected to also help keep red banded stink bug numbers very low this year in the southern half of the state where they occur.. Brown stink bug numbers tend to decline through July. SGSB's typically begin increasing in reproductive stage soybeans in central and south Alabama in late July/August and tend to be the most abundant stink bug from Prattville south to the coast. Traditionally the Green stink bug is much more abundant than the SGSB in the northern half of the state. Late R5 soybean plots at Prattville on August 6 had both Green and SGSB's with the latter being more abundant. Brown marmorated stink bugs (BMSB's) are becoming more common across the state, but numbers of this large SB have still not reached worrisome levels except in a few locations. However, based on the abundance of BMSB's at the Prattville Ag Research Unit it is likely that over time this SB will constitute a much higher percentage of the SB complex in many counties. On August 6 one sample of ten sweep net sweeps across two rows of soybeans next to a corn plot yielded 20 adult BMSB's plus numerous immatures. Fortunately, to date , BMSB's have not been difficult to kill with pyrethroid insecticides. Bifenthrin has provided good control of BMSB's and SGSB's in our tests at Prattville.. Bifenthrin typically provides about 60% control of Brown stink bugs in soybeans. A SB complex at the Prattville Ag unit in 2017 caused a statistically significant 6.8 bu/ac yield loss. The complex was comprised of BMSB's, SGSB's and RBSB's. Soybeans in this study were in the early R5 stage when the first of 3 bifenthrin sprays was applied August 2. Two more applications were made on August 9 and August 24. Sweepnet samples were taken on August 7, 14 and 31 in sprayed and unsprayed plots. Unsprayed plots for the 3 sampling dates averaged a total of 5.1 adult SB's and 7.5 immatures per 15 sweeps during the 3 sampling dates. BMSB's comprised 37% of the adult and 58% of the immatures collected. SGSB's comprised 43% of the adults and 34% of the immatures. Examination of soybean seed after harvest showed that 20.3% of the seed exhibited SB damage in the unsprayed plots and 4% SB damage in plots sprayed 3 times.
There have been many producer complaints about snail and slug issues in row crops. Snails (with a hard shell, see picture) and slugs (without a shell) can cause direct crop damage and contamination in severe cases. Snails produce an acidic material from their foot that dissolves calcium in the soil and allows production of the shell. There are a few other publications listed at the end of this article that may be of help to understand basic biology and identification characteristics for snails/slugs. Growers can to take pictures of their problem and share them with extension agent for basic identification.
Below are management recommendations that are very limited in row crops due to high cost of materials. It is a good idea to check with company representatives for purchasing snail/slug control products, as they are very different from insecticides (note: insecticides will not control snails/slugs!).
Favorable conditions for snails/slugs:
Cultural control tactics:
For more insect management information in peanuts, please visit Alabama Peanut IPM.
Ayanava Majumdar, Extension Entomologist
Kris Balkcom, Extension Specialist, ACES/Auburn University
Rains have continued for the most part in Alabama with almost none of the key peanut production areas marked as drought on the US Drought Monitor website. This is good news for producers, as frequent rainfall and the resulting weather fluctuations do not favor pest activity in general. Based on the insect monitoring data across Alabama summarized in the table alongside, the moth counts in sticky wing pheromone traps are similar to that of 2017. Although most moth activity appears to be increasing slowly, we expect continued buildup of insects based on historic records from the past 10 years (data table). So producers should scout and monitor peanut fields, and be ready to control caterpillars, aphids, and leaf hoppers as necessary.
Ayanava Majumdar, Extension Entomologist
July 18, 2018
Trap catch numbers showed increased bollworm moth activity at the Elmore and Baldwin county trapping sites. Cotton growers across AL should begin monitoring their dual-gene cotton closely for bollworm larvae . Non-Bt cotton has been planted in small plots/strips at Auburn University experiment stations in north, central and south Alabama to serve as sentinel plots for increased bollworm activity. Extension personnel will begin looking at these plantings this week. Four to 6 row strips of non-Bt cotton have also been planted in 4 grower fields in Lawrence and Colbert Counties to serve as sentinel plots. The 3 non-Bt cotton plantings in Lawrence county were inspected on July 16 and no bollworm larvae were detected. Two newly emerged bollworm moths were seen while inspecting the sentinel plantings. Reports indicate bollworm moth activity in Tennessee Valley cotton fields has been light to date with only a very few moths observed in cotton fields. Trap catch numbers at Belle Mina and near Hillsboro have been very low during the last 7 days. Historically, the bollworm moth flight in the Tennessee Valley has begun in either the last week in July or the first week in August. However, in 2017 a few cotton fields required treatment for bollworms during the 3rd week in July in northwest AL.
Most Alabama soils are naturally low in plant-available nutrients and must be fertilized to maintain crop production. Soil testing is critical to improve soil fertility for production of row-crops, specialty crops, and forages. Producers increasingly rely on commercial soil testing laboratories to provide nutrient recommendations for crops. To make best-management decisions for maintaining soil fertility, it is important to understand the basics of soil testing and reporting, whether you use a public or a commercial soil testing laboratory .
The publication, "Interpreting Soil Test Reports for Commercial Labs" Put together by Charles Mitchell, Professor Emeritus, both in Crop, Soil, and Environmental Sciences, Auburn University and Audrey Gamble, Extension Specialist, Assistant Professor explains the basics of soil testing.
In the publication you will learn : 1) how soil testing labs determine fertilizer/lime requirements, 2) explains how/when it is possible to convert to Auburn University fertilizer/lime recommendations using reports from other laboratories, and 3) provides definitions for values which may be included on reports from commercial labs or non-routine reports but are not reported on Auburn University routine soil test report, like CEC and base saturation .
Please see the new ANR fact sheet "Interpreting Soil Test Reports for Commercial Labs" Reference No. ANR-2481 here for more details.
Charles Mitchell, Crop, Soil, and Environmental Sciences, Auburn University
Audrey Gamble, Extension Specialist
Every year brings its own challenges to the farmer. Every year the weather patterns are an unknown and even with the best plans such as: when we plant and what we are going to do and how we are going to accomplish it, those plans always somehow seem to get rearranged. For 2018, it really seems to have been a very challenging spring to get the crop planted and emerged in the time period that we wanted to plant the crop. It has also been a very challenging spring to manage the first post emerge weed control spray. The cooler than normal April delayed many farmers from planting until early May. When May got here it went from cool to hot and there were no spring planting showers to keep the planters going. Some farmers continued to plant while others stopped the planter because of dry soil conditions. When the rains did start back in the later part of May they did not shut off until we got well into June. This was a condition that I refer to as the year of the "light switch May". It was dry and just like that it was wet. As a result this has created a "split crop" for us in Alabama. I was traveling last week in southwest Georgia and it seems that their crop is not as divided as our crop is in southeast Alabama. The end result is an early crop which I estimate to be around 50 percent and a late crop being around 50 percent. With this split crop this certainly presents a challenge when making management decisions. With the earlier planted crop we should be very familiar with crop management of fertilization, weed control, growth regulator use, etc. However with the later planted crop, it is here where I feel that we must not be lulled to sleep thinking that this plant is just like the cotton that was planted in late April or early May. On the earlier cotton we are subject to split apply fertilizer and sometimes not be as aggressive with our growth regulator applications. The crop has "time" we feel like to basically manage itself somewhat and still make it to the finish line. The later planted crop which has been planted in late May through late June and some even in early July is a different animal than the early planted cotton. It may not seem like much but being just a month or more later planted really is a very different crop. Cotton is a 150 day crop basically and develops on heat units, typically around 2500 growing degree 60s. The early crop is slower to develop because of cooler temperatures. The later planted crop has much higher growing degree 60s therefore it will change rapidly.
The management for the later planted cotton should be one of urgency. All the nutrients such as nitrogen should be applied early. Early is somewhere in the 3 to 6th true leaf. Especially dry land cotton. The reason being is because we are in July and it may not rain for two weeks and the nitrogen doesn't activate until you get the rain and the whole time the cotton has been deficient of nitrogen, therefore slowing its growth and development. This is time we do not need to give up on producing this crop. Also, the management of growth regulators is also very important. The very best growth regulator is actually a cotton boll itself. Once the plant begins to load up in fruit the cotton plant is relatively easy to regulate with a growth regulator. Remember cotton is a perennial and we manage it as an annual and often we need growth regulators to channel the plant into a reproductive commitment. Otherwise the plant likes to grow vegetative. Some varieties are more indeterminate than others therefore the utilization of a growth regulator is more important. Stress conditions can also channel the plant into more of a reproductive phase. That's why the application of a growth regulator is more of an art than a science. However, we know that using them is important and the take home message is this late planted cotton doesn't need to grow unchecked in the vegetative stage because the time to make this crop is in a narrower window. We have the time, we typically have the heat units to make an excellent late planted crop of cotton but we do not have the luxury to mismanage the crop and still be fine.
Another item of concern is that this later planted crop will reach peak water demand somewhere around the first of September, which coincides with the peak bloom being roughly 90 days after planting. September is historically the second driest natural rainfall month for Alabama with October being the historical driest month of the year. This certainly concerns me when considering the dryland late planted crop. Nobody has the crystal ball to see the future, but my message is to manage with urgency to not sacrifice any heat units in producing this crop by managing all aspects without delay.
Ext. Regional Agronomist, Auburn University, Wiregrass research and Extension Center
Animal manure has long been recognized as an important source of macro-
(nitrogen, phosphorus, potassium) and micronutrients (boron, zinc, sulfur) for plants. In addition, manure application to agricultural lands can improve soil health and promote nutrient cycling. However, frequent applications of manure often result in phosphorus (P) buildup in soils and pose a risk to the environment via runoff or leaching to water systems. NRCS Nutrient Management Code 590 mandates soil testing and site assessment (using Phosphorous-index) to determine the suitability of a cropland to receive manure/litter. If the average soil test P and P-index for the field falls under "very high" range, manure application is discouraged. Currently the Code 590 is undergoing national revision. Although P index and soil test phosphorus (P) levels are used for environmental assessment of P loss risk, these tools do not provide any information or prediction of the life span of application sites i.e. how long P can be applied safely before the site becomes a source of P to the environment. In addition, many Alabama soils are naturally rich in iron (Fe) and aluminum (Al) oxides, which can potentially render P unavailable for plant uptake as well environmental losses.
The Alabama Animal Waste and Nutrient Management team at Auburn University along with the Alabama NRCS and Soil and Water Conservation Committee are working together to find ways to improve guidelines on P management while minimizing the risk of P loss to the environment. The animal waste and nutrient management team at Auburn University will conduct extensive soil sampling across the State of Alabama to understand the P status of the soils and their potential to act as a source or sink of P to the environment. The soil samples will be used to evaluate the current P application criterion and develop new tools for environmental P loss risk assessment. Growers are encouraged to participate and allow sampling of their fields. The information generated from the research will be shared with growers and will greatly benefit them. No site specific information will be shared with any other individuals/institutions. Please get in touch with the Alabama Animal Waste and Nutrient Management team at Auburn University via email firstname.lastname@example.org or phone 334-734-4937.
Here are some frequently asked question.
Rishi Prasad, Ph.D., Assistant Professor and Animal Systems Environmental Specialist
Kent Stanford, Nutrient Management Specialist; Auburn University, Department of Crop, Soil and Environmental Sciences and Animal Sciences
Excessive rain in May slowed moth activity, but we have detected a sudden increase in pest activity across the state. Beet armyworm moths appear to be the most active in vegetable and peanut fields followed by other species like the fall armyworm, southern and the yellowstriped armyworms (the average moth counts is 5 moths per trap and rising). Armyworms typically start out in hay and pasture fields, or feed on weedy hosts before making a move to the row crops. Armyworms typically lay a large number of eggs in several masses on leaf terminals or stems and flowers covered with body scales making them look fuzzy. Colors of these egg masses may vary from grayish to green – eggs darken as they get closer to hatching. Caterpillars hatch and stay clumped together for several days before dispersing – so, the best control of armyworms is when the caterpillars are small and aggregated. Assuming favorable weather conditions, the fall and beet armyworm moth activity expected to increase five times in the next few weeks with peak activity in August in peanuts.
Corn earworm (or tomato fruitworm), cabbage and soybean looper moths have also started to show some activity in crop fields (1 moth average per trap); those moths lay round eggs singly on leaves and fruits. We can expect rapid growth in the activity of loopers as rows crops begin to grow with more foliage. Historically, tobacco budworm activity appears to be higher in some North Alabama locations with mixed populations in the south. Telling apart corn earworm and tobacco budworm larvae can be difficult, so seek help from extension. The lesser cornstalk borer, a major insect of peanuts, has been found in large numbers in insect traps (71 moths average per trap) but the wet weather is keeping the larvae away from crops. Most moths mentioned are night-flying pests when they are most active for mating and egg laying.
Several insecticides are currently available for caterpillar control in peanuts – they broadly range from general nerve toxins (like synthetic pyrethroids and spinosyns belonging to Groups 3 and 5), feeding inhibitors (selective insecticides in Groups 22 and 28), and growth regulators (selective insecticides in Groups 15 and 18). Remember that the newer selective insecticides in general have longer residual, cause minimal nontarget eggects, and are good rotation products with traditional chemistries available for peanut growers. One of the major concerns with insecticide misapplications is the rise in spider mite infestations caused by the reduction in beneficial mites – spider mites can cause significant yield reduction and are tough to battle in peanuts. Overapplication of insecticides may also destroy big-eyed bugs, lady beetle, and lacewing larvae that can result in aphid and whitefly outbreaks. The attached figure shows caterpillar control materials that can be used with the aim of preventing secondary pest outbreaks. Protection of natural enemies is thus a very critical aspect of the farming system. Consult extension agent for correct insect identification and for developing an IPM plan that is cost-effective for your farm. For more details about individual IRAC Insecticide Groups, visit www.irac-online.org. For more insect management information, please visit Alabama Peanut IPM.
Ayanava Majumdar, Extension Entomologist, Alabama Cooperative Extension System/Auburn University
Kris Balkcom, Extension Specialist, Alabama Cooperative Extension System/Auburn University
Bacterial blight has been reported within the past week on cotton in Georgia and Mississippi. So, far this disease has not been reported in Alabama but probably will make an appearance in the next week or two if current wet weather patterns continue. In Geogia, bacterial blight has been found in DP 1747 and a few additional susceptible or partially resistant varieties.
In past years, I've seen bacterial blight at or shortly after pinhead square on susceptible varieties like DP 1747, so it's not too early for this disease to make an appearance. Current wet weather patterns are quite favorable for onset, spread, and development of bacterial blight. As a result, I would expect to see a this disease show up over the next few weeks in susceptible cotton varieties.
So far, there are no post plant controls for bacterial blight in cotton. I do have a study from Syngenta being conducted in Fairhope looking at foliar treatments to control or suppress bacterial blight. Cotton varieties do differ in their susceptibility to bacterial blight. As noted above, the root knot resistant variety DP 1747 is highly susceptible to bacterial blight. Please refer to this URL for information relating to variety sensitivity to bacterial blight https://lubbock.tamu.edu/files/2018/01/2017-Bacterial-blight-trial-results.pdf. With a few exceptions, the newer variety releases from Phytogen, Deltapine, Stoneville, and some other seed companies are partially or highly resistant to the dominant strain of the causal bacterium (#18) in U.S. cotton, while many of the susceptible varieties are gone. Given favorable weather pattens, however, bacterial blight may damage even varieties reported to be 'resistant'. Rotation with non-host crops may also help as the causal bacterial survives on debris from the previous cotton crop.
Grasshoppers have been a sporadic pest of seedling cotton for 10 or more years. This problem emerged as a result of the conservation movement to reduced tillage. Certain seasons seem to be worse than others and 2018 has resulted in greater concern than more recent years. Growers reported observing high numbers of adult grasshoppers during harvest season in fall 2017. Overwintering populations are influenced by environmental conditions. Rainfall is likely more important than temperatures. Dry winters are favorable for grasshopper population since they overwinter as eggs in the soil. Grasshopper problems are sporadic and almost always associated with reduced tillage fields.
The primary grasshopper that damages cotton is the differential species which also overwinters as eggs in the soil. Eggs hatch from late March throughout April, May and June as soil temperatures rise and spring rains occur. The first nymph to leave the egg pod makes a tunnel from the pod to the soil surface through which the succeeding nymphs emerge. Nymphs feed and grow for 35 to 50 days before becoming adults which can then fly. The nymphs or immatures can only jump. Their development proceeds most rapidly when the weather is warm but not too wet. Mature grasshoppers mate and continue feeding on plants About 2 weeks later, females begin to deposit clusters of eggs in the soil. Soil particles are glued together around the eggs to form a protective pod Each pod may have 25-150 eggs. Most grasshopper species only complete one generation per year.
In fields with historical grasshopper problems, growers may want to take a more preventative approach by adding a grasshopper insecticide to their burn down herbicide. Since not all grasshoppers emerge from the egg stage at the same time, a long residual IGR (insect growth regulator) insecticide could also be utilized. Dimlin has proven to be a good management tool for grasshoppers. It has extended residual that provides good control of immature grasshoppers but will not control adults.
There are no established thresholds for grasshoppers in cotton and will likely never be since their feeding habits are so unpredictable. Some fields and some years may have grasshopper damage while other fields and years have the same level of grasshoppers but no damage. Preventative insecticide applications for grasshoppers are a judgment call. When grasshoppers are observed, and cotton is in the susceptible stage, treatments can be based on the risk level that an individual grower is willing to take.
Grasshopper problems are greater in lighter soils or soils with higher sand content. Damage often occurs in the same fields or farms from year to year. Grasshopper damage as stated is unpredictable but can potentially threaten a stand. Grasshoppers may feed on foliage, but most economic damage occurs when grasshoppers feed on the mainstem of emerging (in the crook or cracking stage) seedlings. In some cases, grasshoppers may completely sever the stem, but more often they will chew partially through the stem weakening the plant which will fall over at the feeding site.
Most all cotton insecticides will control immature grasshoppers when applied at a low labelled rate. Later into the spring, adult grasshoppers are very difficult to control with any insecticide, even at a high labelled rate. Acephate (Orthene) at 0.6 lb. active per acre has proven to be the most effective grower treatment for adult grasshoppers.
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