{"id":335,"date":"2019-05-06T10:23:05","date_gmt":"2019-05-06T14:23:05","guid":{"rendered":"http:\/\/site.extension.uga.edu\/benhillcoag\/?p=335"},"modified":"2019-05-06T10:23:58","modified_gmt":"2019-05-06T14:23:58","slug":"may-cotton-team-newsletter","status":"publish","type":"post","link":"https:\/\/site.extension.uga.edu\/benhillcoag\/2019\/05\/may-cotton-team-newsletter\/","title":{"rendered":"May Cotton Team Newsletter"},"content":{"rendered":"

Crop Progress and Assessing Plant Stands for Replanting<\/strong>
\n(Freeman)<\/strong>
\nAs of April 29th, approximately 12 percent of Georgia\u2019s cotton crop has been planted according to the
\nUSDA NASS crop progress report. This is significantly ahead of our previous five year\u2019s average of 7
\npercent. Although wet through most of the winter and spring, conditions in most parts of the state
\nhave become dry, and much of our planted acres tend to be on our irrigated lands. These dry
\nconditions may be favorable for field work however, rainfall is needed if we are to have adequate soil
\nmoisture to ensure proper stands on a lot of our dryland acres. Fortunately it looks like we will get
\nsome much needed precipitation as the 10-day forecast shows high chances for rainfall for much of
\nour cotton growing regions of the state.
\nIn a perfect world, we would only plant cotton during optimal conditions however, in the real world
\ncotton is often planted in harsh or sub-optimal conditions for a variety of reasons. It is important to
\ncheck and evaluate your cotton stands soon after emergence so that any decisions on replanting can
\nbe made quickly as these decisions can become more difficult as more time passes. One of the first
\nthings that needs evaluating is the overall plant population across the field. This can be recorded
\nseveral ways but a plants\/ft average needs to be recorded from several\/many different areas of the
\nfield to get a good representative sample of the field\u2019s plant population. The second part of the stand
\nassessment is noting the occurrence of 3\u2019 or greater gaps between plants. A field may have a lower
\nthan \u201coptimal\u201d plant population but if most of the plants are evenly spaced then very little if any yield
\nlosses may occur. Fields with a high number of 3\u2019 or greater gaps have a higher likelihood of lower
\nyield potential and delayed maturity.
\nWhen deciding if the current stand is adequate or if replanting will be needed considerations must
\nbe taken for the extra costs or seed, fuel, labor, additional herbicides and insecticides as well as
\nhidden costs like the decrease in yield potential from a later planted crop. Other questions that
\nshould be asked are: How uniform is the stand across the field? Should I replant the entire field or
\nonly spots? If I replant only parts of the field, how will the difference in maturity affect me later in the
\nseason with PGR management and defoliation?
\nThe original preemerge herbicides should also be taken into account. If Warrant was used as a PRE,
\nreplanting should be delayed for 14 days as long as tillage (strip till equipment) is done and 21 days
\nif no tillage is done to avoid serious injury to the replanted crop.<\/p>\n

Herbicides and dusting in cotton can be a mighty challenge!<\/strong>
\n(Culpepper)<\/strong>
\nHerbicide injury and weed control are both challenging when dusting in cotton and the topic deserves
\ndiscussion.
\nThe most effective approach to minimize cotton injury from preemergence (PRE) herbicides is to
\nplace the cotton seed in moist soil where it can imbibe (absorb) clean water free of herbicides.
\nNext we need our cotton roots to \u201cout run\u201d the herbicide as the herbicide is moving down into the soil with
\nrainfall or irrigation. When placing cotton seed in dry soil and then applying a PRE herbicide, it is
\nlikely impossible for water to get to the seed without being contaminated with the herbicide.
\nHowever no two herbicides pose the same challenge under these conditions; here are a few thoughts
\nwith several products:<\/p>\n

1. Reflex moves very effectively in water thus it is the product most likely to reach the seed at higher
\nconcentrations. Although that is not beneficial for the cotton seed, it is very beneficial for weed
\ncontrol as the product is activated more effectively with lower amounts of rainfall or irrigation than
\nother cotton herbicides. Additionally, our research has shown Reflex to sit on the soil for 17 days
\nbefore being activated and then still providing about 90% control of the pigweed emerging after
\nactivation.<\/p>\n

2. Warrant poses a unique challenge, if the encapsulation breaks down releasing the active ingredient
\nprior the cotton plant emerging then injury can be quite significant. It is the encapsulation of Warrant
\nthat provides us the ability to use it \u201csafely\u201d PRE in cotton. Any time one is uncertain of cotton
\nemergence within 5 or 6 days of applying Warrant, one may want to consider other options. Ideally
\nWarrant needs around a half inch of rain for activation and our research has shown it to still be quite
\neffective on pigweed after sitting on the soil and waiting 11 days for activation.<\/p>\n

3. Diuron will move down to the seed less aggressively than Reflex but if a heavy rain occurs within
\na few days of dusting the cotton in and applying diuron, injury will be much greater than normal.<\/p>\n

4. Brake likely poses the least damage potential to cotton in this environment but the herbicide may
\nnot perform on weeds properly until a half inch or more of rainfall occurs.<\/p>\n

Obviously, dusting cotton in and applying PRE herbicides is far from ideal. The next thought from
\nevery grower is, of course, I just want apply herbicides after planting. This thought is extremely scary
\nwhen considering the monumental challenges our family farms face with herbicide resistance in
\nPalmer amaranth. If one does follow this path of not using PRE herbicides, there are several key
\npoints to consider. First, there must be no weeds emerged when the cotton seed is placed in dry soil.
\nIn theory, no additional weeds should emerge until it rains. Second, the first postemergence
\nherbicide application should occur as soon as the cotton is fully emerged (do not wait to see weeds
\nat 70 mph from the road); the treatment must kill emerged weeds (Palmer and spiderwort) and must
\ninclude residual herbicides. Third, a second postemergence herbicide application should be made 14
\nto 18 days later and again include a residual product. And finally and absolutely essential, is that the
\nlayby application is made with hoods or a layby rig improving weed coverage and control while
\nminimizing cotton injury. The layby application should include conventional herbicide chemistry
\nsuch as diuron, Caparol or Cotoran; also include Envoke if help is needed with morningglory or
\nnutsedge.<\/p>\n

Thrips Foliar Sprays (Roberts)<\/strong><\/p>\n

Thrips are consistent and predictable insect pests of seedling cotton in Georgia.\u00a0 Preventive insecticides are recommended at planting to reduce thrips infestations and seedling injury.\u00a0 Supplemental foliar insecticides are needed in some environments and applications should be based on scouting and thresholds.\u00a0 The need for supplemental foliar insecticide is dependent upon the severity of thrips infestations, the at-plant insecticide used, and the rate of seedling growth.<\/p>\n

At-plant insecticide options include in-furrow granule applications of aldicarb, in-furrow liquid applications of imidacloprid or acephate, and commercial seed treatments of imidacloprid, thiamethoxam, and acephate.\u00a0 Imidacloprid seed treatment is the most common at-plant insecticide used.\u00a0 Thrips control and residual activity is greater for in-furrow granules and liquids compared with the seed treatments.\u00a0 We would expect 3-4 weeks activity with in-furrow options and 2+ weeks of activity with the imidacloprid seed treatment.<\/p>\n

The Thrips Infestation Predictor for Cotton (TIPs) Tool uses planting date, temperature, precipitation, and knowledge of when and how intense thrips infestations will be to predict risk of thrips injury to cotton for specific geographic locations.\u00a0 For many areas, the tool is predicting thrips infestations to be similar to those observed during 2017 and 2018 which were both relatively low pressure years.\u00a0 The TIPs Tool can be found at the following link:<\/p>\n

https:\/\/climate.ncsu.edu\/CottonTIP<\/a><\/u>.<\/p>\n

Vigor or the rate of seedling growth influences seedling injury from thrips.\u00a0 Thrips initially feed on the underside of cotyledons; damaged cotyledons will appear silvery on the lower surface of cotyledons.\u00a0 The majority of thrips eggs are laid on the cotyledons and it takes about 5-6 days for an egg to hatch.\u00a0 Once a terminal is present thrips will move to and feed on unfurled leaves in the terminal.\u00a0 As the leaves unfurl and expand the characteristic crinkling and malformations become obvious.\u00a0 A rapidly growing seedling may unfurl a true leaf every 3 days where as a seedling which is stressed may take 4-5 days to unfurl.\u00a0 Again, thrips are feeding on the unfurled leaves so thrips feed for a more extended time on the same unfurled leaf of a stressed plant than a rapidly growing plant.\u00a0 The same infestation of thrips will create more damage on a slow growing plant.<\/p>\n

The decision to use a foliar insecticide to supplement at-plant insecticides for thrips control should be based on scouting.\u00a0 Scout thrips by randomly pulling a seedling and \u201cslapping\u201d the seedling against a piece of paper or box to dislodge the thrips.\u00a0 Do this on several plants and determine the average number of thrips per plant.\u00a0 Be observant for immature thrips when making counts.\u00a0 Immature thrips are wingless and cr\u00e8me colored.\u00a0 Adult thrips are usually brownish or almost black in appearance and have wings (depends on species, tobacco thrips is the most common thrips species infesting cotton and adults will be dark brown or black).\u00a0 The threshold for thrips is 2-3 thrips per plant with immatures present.\u00a0 The presence of numerous immature thrips suggests that the at-plant insecticide is no longer providing acceptable control (i.e. thrips eggs laid on the plant, egg hatched, and immature thrips is surviving).\u00a0 Foliar insecticide options include the systemic insecticides Orthene, Bidrin, and dimethoate.\u00a0 Note that these products are systemic.\u00a0 Pyrethroids will not provide acceptable control thrips in cotton.<\/p>\n

Economic damage from thrips rarely occurs once seedling reach the 4-leaf stage and are growing rapidly.\u00a0 It is important that we make thrips decisions early in the plants development.\u00a0 Seedlings become more tolerant to thrips feeding in terms of yield potential with every true leaf it puts on.\u00a0 1-leaf cotton is much more susceptible to yield loss than 3-leaf cotton.<\/p>\n

 <\/p>\n

Managing Nematodes in Your Cotton Crop: What you do now<\/strong>
\naffects everything you do later (Kemerait)<\/strong>
\nWe had a very mild winter this year. Mild winters may be nice in reducing our power bill; however
\nextended periods of very cold soil temperatures are essential for reducing nematode populations in
\nthe upcoming field season. I don\u2019t believe we had enough cold weather this year and it could make
\nnematode problems more severe for our cotton farmers.
\nIf plant-parasitic nematodes are likely to be a problem in a cotton field this season, then the grower
\nhas a very brief window of opportunity to effectively manage this pest. Southern root-knot, reniform,
\nsting, and Columbia lance nematodes all damage our cotton crop in Georgia and, while growers may
\nnot find management options convenient, protecting the crop from nematodes is an essential step to
\nprotecting yield. Nematodes begin to affect the root system of the cotton crop very soon after
\ngermination. If the developing taproot and root-system is not protected, then all other production
\nefforts throughout the remainder of the season are compromised as the damaged plants can never
\nfully recover.
\nThere are important steps necessary to reduce the risk of nematodes to a cotton crop and to protect
\nthe crop once the seed is planted. It is critical to remember that once the furrow is closed, nearly
\nevery management decision has been made and the grower will have to \u201clive with\u201d the results
\nthroughout the season and on to harvest.<\/p>\n

Step 1. Practice good crop rotation to reduce parasitic nematode populations in a field. Peanut is an
\nexcellent rotation crop for cotton as peanut is not a host for the reniform, Columbia lance, or southern
\nroot-know nematodes. Corn is not a host for the reniform nematode. Soybean is a host for the
\nsouthern root-knot and reniform nematodes; however if a grower planted a \u201cnematode-resistant\u201d
\nvariety in the previous season, then the impact of the nematodes on the future cotton crop should be
\nreduced.<\/p>\n

Step 2. Take soil samples, optimally in the fall of the previous cropping season, to assess both the
\ntypes of nematodes and population size in a field. To be able to make the best management decisions,
\nit is important to know not only which kinds of nematodes are in a field, but also how many of them
\nare there. Growers could take samples now that soil temperatures have risen; however nematode
\ncounts may still be deceptively low and misleading as far as best management options.<\/p>\n

Step 3. Consider planting a root-knot nematode resistant variety, such as DP 1747 B2RF, Phytogen
\n480 or Phytogen 580. These varieties are not resistant to reniform, sting or Columbia lance
\nnematodes; however they can have a tremendous impact when planted where southern root-knot
\nnematode is a problem. Planting one of these resistant varieties in a field infested with root-knot
\nnematodes will accomplish two things. First, damage from root-knot nematodes will be minimal, if
\nit occurs at all. No nematicides are needed. Second, the root-knot nematodes will be unable to build
\nin the field, so populations will be lower for the next cotton crop.<\/p>\n

Step 4. If a grower chooses not to plant a root-knot nematode resistant variety, either because he
\npreferred another, susceptible, variety or because reniform, sting or Columbia lance nematodes were
\nthe problem in the field, then he must consider using a nematicides to protect the crop. To make the
\nmost informed decision about which nematicides to use, the grower should have some idea about the
\nsize of the nematode population in the field. This is best accomplished with results from fall
\nnematode counts. Samples taken in the spring before planting, but after soils warm, could give some
\ninformation if nematodes are found in the sample. However if nematodes are not found in the sample
\nthen this may simply be because they have not yet built to a detectable level following the colder
\nwinter months.
\nWhere parasitic nematodes are well-above \u201cthreshold\u201d levels, there is no nematicides that can
\nperform as effectively as Telone II (3 gal\/A). Telone II is a fumigant that must be applied when the
\nsoil is neither too wet or too dry. Typically Telone II is applied 7 to 14 days ahead of planting;
\nhowever when soil conditions are right and heavy rain is not expected within 3-4 days following
\nplanting, Telone II can be applied at the same time as the seed is planted.
\nIn fields where Telone II will not be used, or where nematodes are at a \u201cmoderate threat\u201d, growers
\nshould consider using AgLogic (5-7 lb\/A) or Velum Total (14-18 fl oz\/A). Both products protect the
\ncotton crop against nematodes and thrips. Though results from nematicide trials are notoriously
\nvariable, I am comfortable with the recommendation that Velum Total (16-18 fl oz\/A) is gernally
\nequivalent in performance to AgLogic (5 lb\/A). Where pressure from nematodes is severe, it is my
\nobservation that AgLogic (7 lb\/A) offers greater protection than does Velum Total. But, of course,
\nthat additional protection comes at a cost.<\/p>\n

Seed treatment nematicides, to include AVICTA Complete Cotton, COPeO Prime, Bio ST, Nemastrike
\nall are convenient tactics for managing nematodes; however they may not be enough. I have
\nsignificant data for AVICTA Complete Cotton and COPeO Prime and an increasing volume of data for
\nBIO ST. I have limited data for Nemastrike. Seed treatment nematicides are most appropriate for
\nlow levels of nematodes in a field. As populations of nematodes increase, the benefit of the seed
\ntreatments, as compared to Telone II, AgLogic, or Velum Total, is lost. Also, performance of some
\nseed treatment nematicides in Georgia may not match that reported in advertisements.
\nI do not have data to show the value of combining use of a seed treatment nematicide with either
\nVelum Total or AgLogic; however I generally do not think any additional benefit in yield will offset
\nthe added cost of the combination treatment.
\nOnce the furrow is closed, growers have only one additional treatment option and that is either
\nVydate-CLV or RETURN XL as a foliar-applied nematicide at approximately the 5th to 7th true leaf
\nstage. This treatment should be in addition to an earlier nematicides treatment and not as a \u201cstand
\nalone\u201d treatment. Results with Vydate-CLV have been mixed, but it seems most promising where
\nreniform nematodes are a problem.<\/p>\n","protected":false},"excerpt":{"rendered":"

Crop Progress and Assessing Plant Stands for Replanting (Freeman) As of April 29th, approximately 12 percent of Georgia\u2019s cotton crop has been planted according to the USDA NASS crop progress report. This is significantly ahead of our previous five year\u2019s average of 7 percent. Although wet through most of the winter and spring, conditions in […]<\/p>\n","protected":false},"author":234,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20,23,26,22,21],"tags":[],"class_list":["post-335","post","type-post","status-publish","format-standard","hentry","category-cotton","category-disease","category-fertility","category-herbicides","category-insects"],"_links":{"self":[{"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/posts\/335","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/users\/234"}],"replies":[{"embeddable":true,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/comments?post=335"}],"version-history":[{"count":2,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/posts\/335\/revisions"}],"predecessor-version":[{"id":337,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/posts\/335\/revisions\/337"}],"wp:attachment":[{"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/media?parent=335"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/categories?post=335"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.extension.uga.edu\/benhillcoag\/wp-json\/wp\/v2\/tags?post=335"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}