Printable List of County Offices (PDF)
Prior to the recent dry weather this past week, the generally wet and cloudy weather patterns over much of August across Alabama were favorable for the development of foliar diseases in cotton and peanut. The disease risks in both crops was enhanced by the frequent showers and wet soils which interfered with routine protective fungicide applications.
In peanut, early leaf spot has appeared in Georgia-09B and Georgia-16HO at the Wiregrass Research and Extension Center. In addition, late leaf spot was found at the Gulf Coast Research and Extension Center and production fields in Georgia-06G in Central AL. If showers continue into September, expect to see both leaf spot diseases getting a foothold in peanuts across the state, particularly in those fields where fungicide applications were delayed by wet weather.
Early peanuts that will mature in the next two or three weeks probably will have few leaf spot issues. Typically, later maturing peanuts are more at risk from early and late leaf spot control failures due to higher inoculum levels encountered in September and October.
Control of ongoing leaf spot epidemics is exceptionally difficult. When leaf spot incited defoliation is begun, producers are advised to 1) shorten application intervals from 14 to 10 days, 2) use aerial application to stay on schedule, 3) tank mix 0.75 to 1 pt/A chlorothalonil (Bravo, Echo, Equus, etc.), methyl thiophanate, tebuconazole, or other generic leaf spot fungicides, with their premium leaf spot/white mold fungicide, or 4) apply 6 to 8 fl oz/A Priaxor or 3.4 fl oz Miravis alone or in combination with Alto @ 5.5 fl oz/A or 7.3 or 9.5 oz Elatus. In 2017 Alabama field trials, the best leaf spot control was obtained with Miravis when tank mixed with Elatus. In the past, pyraclostrobin (Headline) at 9 fl oz/A also provided good leaf spot protection. However, tolerance to strobilurin fungicides is an issue in some peanut-production areas, so this fungicide along with azoxystrobin may no longer provide effective leaf spot control. Generic formulations of azoxystrobin alone or in combination with a triazole fungicide (i.e. flutriafol, tebuconazole, or tetraconazole) or chlorothalonil as well as pyraclostrobin alone are available.
If leaf spot control is good, producers need to continue protective fungicide applications need to continue up to 14 days before harvest, particularly in late maturing peanuts and always watch for a late summer tropical storm.
One disease that has not yet popped up is peanut rust, which typically shows up first in Baldwin or Mobile Co, particularly in later maturing peanuts. Last fall, this disease hit a late planted peanut cultivar trial in DeKalb Co! Once established, this disease is much more difficult to control than leaf spot diseases. Rust 'hot' spots look just like spider mite damage but appear well away from field borders or light poles. Producers in southwest AL need to start scouting for rust 'hot' spots. If rust does appear, apply 1.5 pt/A chlorothalonil at 7 to 10 day intervals. The efficacy of premium leaf spot/white mold fungicides under severe rust pressure is largely unknown. To my knowledge, we've not had many opportunities to screen many of the new fungicides for peanut rust control.
The past year or two, foliar diseases have not been a major issue in Alabama cotton. They are now. With the wet weather patterns over the past few weeks coupled with rank cotton, target spot is a real threat to significantly reduce lint yield in some Alabama cotton fields. Damaging outbreaks of this disease have been reported across Georgia. Yield losses to this disease on a susceptible cultivar can hit 400 lb lint per acre. That translates into a $320 to $360 per acre income hit at this year's market price. Fortunately, the majority of Alabama cotton acreage is cropped to less susceptible to partially resistant cultivars (primarily Deltapine 1646 B2XF among others). Recently, fields of this cultivar in Butler and Escambia area were almost target spot free. However, OVT full season flex cotton cultivar trials at WGREC and Prattville along with trials at Brewton, Prattville, and Tallassee, which include many 'partially' resistant cultivars, are getting plastered by target spot. Defoliation levels in the range of 75% along with sizable yield losses are anticipated by September 1. The cotton in all of the above trials has rank growth; in contrast, there's little disease activity in trials (i.e. GCREC and Field Crops) where the cotton has not lapped the middles. Rank top growth is a must for severe target spot outbreaks and significant yield loss.
In addition, areolate mildew (false mildew) has made an early appearance in Alabama cotton and probably more of an issue than target spot. In the past, significant outbreaks of this disease have been few and far between but this disease caused concern last year in Georgia. Little is known of the impact of weather on disease development or the susceptibility of cotton cultivars to this disease. Disease outbreaks were observed over several years in a cotton-sweet sorghum rotation study at Brewton (BARU). There, disease intensity was higher in continuous cotton than cotton cropped behind sorghum. Also, differences in the reaction of Phytogen 499WRF and Deltapine 1252 B2RF were noted. Prior to this year, areolate mildew has not been a serious issue in any cotton fungicide screening studies at Brewton, Field Crops, or GCREC.
Areolate mildew outbreaks have primarily been reported this year in West Central and Central Alabama. Severe defoliation has been observed in some fields, particularly in West Central AL, where a sizable percentage of the cotton acreage has been treated with a fungicide. This disease has developed in some of the OVT cultivar trials and other cotton cultivar trials at other South and Central AL locations but disease intensity has been low. No obvious differences in the reaction of cotton cultivars to areolate leaf spot have been observed.
Unlike target spot, the relationship between areolate mildew-incited defoliation and yield has not been established. However, the defoliation pattern for early onset areolate mildew appears to be similar to target spot, so I would anticipate the yield loss potential when defoliation levels exceed 50% are probably similar for these two diseases.
At this point, early May cotton has reached the 7th week of bloom and will no longer benefit from fungicide protection. In Alabama, trials have shown that a pair of late applications of Headline or Priaxor (5th and 7th week of bloom) can give excellent yield protection and good control of target spot. If wet weather patterns return, there may be issues with this disease in late May and June-planted cotton. Unfortunately, there's no information on the performance of single late fungicide application programs against either disease. In a Georgia trial some years back, Headline gave good control areolate mildew. Information on the efficacy of other fungicides against areolate mildew is a bit thin. I expect that Priaxor, which contains pyraclostrobin, will also have good activity against this disease as would azoxystrobin (Quadris, Topguard EQ, and generic products), and Elatus (azoxystrobin + benzovindiflupyr). In some Deltapine 1646 B2XF in Butler Co., a single application of azoxystrobin appeared to have given good control of areolate mildew. Areolate mildew has not hit any of the fungicide screening trials at Brewton, Field Crop Unit, or Gulf Coast, so fungicide efficacy data for this disease will not be generated at those locations this year.
One saving grace is the onset of drier weather patterns over the next 10 days across much of the state. Those conditions should slow if not stop target spot and areolate mildew activity in cotton and will help suppress leaf spot diseases in peanut.
Agronomic Crops, Professor
Taproot decline (TRD) was detected in a soybean field near Belforest in Baldwin County this week. The disease, first detected in Alabama in 2016, has now been found in 21 counties across the state. The first reports of TRD in the United States were from Arkansas, Louisiana and Mississippi in 2007. However the pathogen was not formally identified until 2017 (https://www.plantmanagementnetwork.org/pub/php/volume18/number1/PHP-01-17-0004-RS.pdf). Taproot decline is caused by a previously undescribed species in a genera of wood-rotting fungi commonly seen in forests called "dead man's fingers" (Xylaria arbuscula). Foliar symptoms of TRD may be easily confused with other soil-borne diseases such as Sudden death syndrome (SDS), charcoal rot and southern blight. TRD infected plants exhibit interveinal chlorosis in the middle canopy prior to bloom, and foliar yellowing in the upper canopy at full pod. Infected plants have blackened roots which often break off below the soil line when pulled from the ground.
Symptoms of TRD include foliar yellowing and blackened taproot.
Taproot decline has a wide distribution throughout the southern soybean production area and is increasing in importance. Little is known about the causal organism or the disease. We are currently working with Mississippi State, Louisiana State University and University of Arkansas to survey for the pathogen and determine best management practices for TRD. Research on TRD is currently focused on identifying varietal resistance to TRD in soybean, determining fungicide effectiveness, crop rotation & tillage options, identifying alternative hosts for the pathogen, and estimating yield loss to the disease. If you suspect you have TRD in your field, please send whole plant samples to the Auburn University Plant Diagnostic Lab with the following information: field location, variety, plant-growth stage and field history. This will help us better understand the distribution of TRD within Alabama.
Edward Sikora and Kassie Conner
Alabama Cooperative Extension System
August 26, 2018: So far numbers of acres treated for soybean loopers (SBL's) are less than normal in Alabama but the recent statewide increase in SBL moth trap catch numbers and the increase in the number of small SBL's in test plots in Baldwin and Escambia counties indicate the possibility of more fields requiring treatment during the next two weeks.
Soybean looper moth trap catches at 5 trapping sites in the state have increased steadily since the last week of July. (See Table below).
Average trap catch numbers for 5 sites were as follows: 4th week of July = 102, 1st week of August = 135, 2nd week of August = 188; and 3rd week of August = 297. Soybean loopers have been sprayed in most soybean fields in Baldwin county and numbers of small loopers present in test plots at Fairhope having soybeans in the early R5 stage have increased significantly during the past week. These plots were treated earlier with a foliar neonicotinoid spray and Amdro fire-ant bait to reduce beneficals, but unsprayed fields of soybeans at the Fairhope research station also had defoliation levels of 20% due to SBL's on August 23. Drop cloth samples taken on 8/23 showed total numbers of SBL's per 3 row ft ranging from 55 to 80 at Fairhope. About 75% of these larvae were 3rd instars or younger and defoliation was close to 10%. This was up from 5% the previous week. SBL numbers at the Brewton station were also increasing with unsprayed test plots averaging 38 SBL larvae per 3 row feet with 75% of the worms being small. Defoliation averaged 5% to 10% in these Brewton plots, up from 1 to 4% the previous week. We have also had reports of SBL's being sprayed in Pickens, Dallas and Jackson counties. Reports from Monroe county, northwest and north central AL indicate very low levels of loopers present to date. Reports indicate Green cloverworm numbers have also crashed across the state after reaching treatable levels in some fields. Velvetbean caterpillars were very rare at both Fairhope and Brewton on the 23rd and 24th of August, respectively. Our 2018 insecticide tests at Brewton have shown that Besiege, Intrepid Edge and Prevathon have all provided good control of soybean loopers at this site. We have also had reports of Fall armyworms infesting pastures/hayfields, athletic fields and lawns across central and south Alabama. Grass that has been well-fertilized and watered is especially attractive to Fall armyworms.
Tim Reed, Extension Entomologist and Ron Smith Professor Emeritus of Entomology
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 email@example.com 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
Copyright © 1997 -
2018 by theAlabama Cooperative Extension System
Alabama A&M University and
All Rights Reserved. – firstname.lastname@example.org
Legal Disclaimer – Privacy Statement
Cookie Acceptance Needed