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Publication #PI220

Florida Crop/Pest Management Profile: Cotton1

Mark A. Mossler2

Figure 1. 

A cotton field at sunrise in North Florida, October 2004.


Credit: Marisol Amador, IFAS/UF
[Click thumbnail to enlarge.]

Production Facts

  • In 2007, there were 207 cotton farms in Florida with a total reported acreage of 72,422 acres.

  • More than 90 percent of Florida acreage planted in cotton in 2007 was reported as being non-irrigated. The yield in irrigated cotton (576 pounds per acre) planted in Florida that year was nearly 100 pounds less per acre than that of non-irrigated cotton (672 pounds per acre)(1).

  • In 2008, Florida cotton production was 122,000 bales (nearly sixty million pounds) harvested from 65,000 acres. The per-pound price (52 cents) growers received equated to a crop value that year of slightly more than $30 million.

  • Florida acreage planted in cotton in 2009 (65,000 acres) is slightly less than that planted in cotton in 2008 (67,000 acres) (2).

  • Florida cotton production has increased from a low in the early 1990s of approximately 75,000 bales. In 2006, Florida cotton production peaked at 166,000 bales (3).

  • In 2008, Florida ranked fifteenth out of the 17 states reporting cotton statistics. Florida accounts for one percent of cotton grown in the United States (4).

  • In 2008, the average yield for the U.S. cotton crop was 803 pounds per acre. For cotton grown in Florida that year, however, the average yield was 916 pounds per acre (2,5).

Production Regions

All of the cotton acreage in Florida is in the Panhandle. Jackson and Santa Rosa Counties account for two-thirds of the cotton production in Florida. Six other counties — Calhoun, Escambia, Holmes, Okaloosa, Walton, and Washington — account for most of the remainder (6).

Figure 2. 

A combine harvests cotton in Chipley, Fla., October 2006.


Credit: Josh Wickham, IFAS/UF
[Click thumbnail to enlarge.]

Production Practices

Total cotton-harvested acres in the U.S. have decreased greatly since historic highs, but growers have maintained and even increased production levels because of higher yields.

Cotton is the fruit of the cotton plant (Gossypium hirsutum) and a natural cellulosic fiber.

In its native habitat, cotton is a woody perennial plant that does not die in the fall. Instead, the plant becomes dormant during periods of drought and resumes growth with the return of favorable rainfall. This characteristic is partially responsible for cotton’s reputation as a dry-weather crop. Over time, cotton has been adapted and bred to react as an annual (7).

Figure 3. 

Cotton balls grown in North Florida.


Credit: Sally Lanigan, IFAS/UF
[Click thumbnail to enlarge.]

Cotton is a slow-growing crop that can be prone to competition from plants and feeding by insects and nematodes. Cotton has the highest chemical input historically for a row crop, and, consequently, much effort has been placed into pest management strategies for this crop. In a survey in 1997, just prior to the introduction of genetically modified cotton, more than half of Florida cotton growers who responded reported that total expenses for pest management — including application labor, materials and equipment — represented 20 percent or more of their total direct costs of production. The remainder of that survey's respondents indicated their total expense for pest management was between 11 and 20 percent (7).

However, contemporary pest management for cotton has been simplified to a combination of prophylaxis during early seedling development and pest toxin production during plant growth. Chemical needs are still reported for the drying and harvest preparation at the end of the season.

Because cotton is planted by seed, seed treatments have become the foundation of management plans for nematode, soil insect, and soil disease. Mid- and late-season lepidopteran management is often less of a concern with B.t. cotton, which has been highly adopted. Plant-feeding bugs are now the primary pest that may require applications of non-selective materials.

Glyphosate-resistant cotton has also been widely adopted in Florida production. Whereas weed management previously depended on an average of four herbicides, glyphosate now controls the cotton-weed spectrum in Florida, as glyphosate-resistant weeds have not yet been identified in the state. A dinitroaniline herbicide may be used for early-season weed control and some other may be employed for specific weed situations. Most cotton is on a cotton/peanut rotation with one or two years between peanuts (8,9).

Few fungicides are applied during the growing season. Approximately a third of Florida growers use a strobilurin fungicide for hard lock and leaf spots (10).

Worker Activities. Cotton is cultivated mechanically. Consequently, there are no worker activities for this crop.

Insect/Mite Management

With the advent of modified cotton, insect pressures have changed while mites remain at the same level of concern. Less important are insects that try to reproduce inside the plant (such as the boll) or chew on the plant, while insects that pierce-feed on the maturing bolls (mostly aphids and bugs) have become the primary pests (9).

Melon/Cotton Aphid (Aphis gossypii)

In the South, at least as far north as Arkansas, sexual forms are not important in this aphid. Females continue to produce offspring without mating so long as weather allows feeding and growth. Unlike many aphid species, melon aphid is not adversely affected by hot weather. Melon aphid can complete its development and reproduce in as little as a week, so numerous generations are possible under suitable environmental conditions (11).

Melon aphid has a very wide host range. At least 60 host plants are known in Florida and perhaps 700 host plants worldwide. This aphid can be a serious pest on watermelons, cucumbers, and cantaloupes, and, to a lesser degree, on squash and pumpkin. In the South, cotton is an important host, which explains this pest's second common name, “cotton aphid (11).”

Melon aphid feeds on the underside of leaves or on the growing tip of vines, sucking nutrients from the plant. Foliage may become chlorotic and die prematurely. The aphid's feeding also causes considerable distortion and leaf curling, hindering photosynthetic capacity of the plant. In addition, these aphids secrete a honeydew that provides a substrate for growth of sooty mold, further impairing the photosynthetic capacity of the foliage (11).

Tarnished Plant Bug (Lygus lineolaris)

The tarnished plant bug is among the most damaging of the true bug group that affects cotton and is known to transmit plant diseases. This bug uses needle-like mouthparts to extract plant juices. Their feeding causes terminal growth to be yellowed or distorted, thereby reducing plant growth and causing plants to appear unthrifty. Leaves from damaged buds are sometimes ragged and discolored. Flowers from damaged buds sometimes fail to develop on one side, or the whole bud aborts. The appearance of plant parts damaged by feeding from this bug is described by terms such as “crazy cotton” and “bushy-top.”

Adult and nymph tarnished plant bugs feed by sucking plant juices, and a watery saliva is simultaneously injected into the feeding site to aid in the breakdown of plant tissues. Symptoms appear within a few weeks after feeding injury. Generally, apical dominance is lost, and weak multiple leaders appear (12).

Whitefringed Beetles (Naupactus spp.)

Originally from South America, three species of this beetle comprise the complex observed in Florida. Whitefringed beetles have been associated with more than 385 plant species. The most common hosts are cotton, peanut, okra, and other members of the bean family. The persistence of whitefringed beetle populations in an area of land is noteworthy and speaks for the difficulty of achieving control (13).

Means of Control

Chemical Control

The high adoption of genetically modified, insect-resistant cotton has greatly altered the manner in which chemical products are used. Fewer materials are applied less frequently (2), and a number of compounds are used as seed treatments.

Insecticides and miticides registered for use on Florida cotton include the following: abamectin, acephate, acetamiprid, aldicarb, azadirachtin, Bacillus thuringiensis, Beauveria bassiana, bifenazate, bifenthrin, buprofezin, carbaryl, chlorpyrifos, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, dicofol, dicrotophos, diflubenzuron, dimethoate, dinotefuran, endosulfan, esfenvalerate, etoxazole, fenpropathrin, fenpyroximate, flonicamid, hexythiazox, imidacloprid, indoxacarb, insecticidal oils, insecticidal soaps, kaolin, malathion, methidathion, methomyl, methoxyfenozide, methyl parathion, naled, oxamyl, oxydemeton, phorate, phosmet, profenfos, proparagite, pymetrozine, pyrethrins, pyriproxyfen, spinosad, spiromesifen, sucrose octanoate, sulfur, tebufenozide, thiamethoxam, and thiodicarb.

About half of the planted cotton seed is treated with aldicarb (as a soil application) or a seed treatment containing either thiodicarb + imidacloprid or thiamethoxam + abamectin. The trend towards using aldicarb is decreasing while use of treated seed is increasing (14). Typically one application is made during bloom unless the crop historically suffers from hardlock, in which case one-to-three applications (with a fungicide) may be made during this period (9,10). The insecticide dicrotophos is applied to a large portion of the crop (15).

Cultural Control

The most commonly practiced form of cultural pest control is crop rotation. The planting of grasses (particularly Bahiagrass) creates an environment that is not conducive to cotton-pest feeding (11,12).

Weed and Plant Growth Regulators

Weed Pests

Since cotton is a slow-growing plant, weeds can quickly out-compete this crop if weed management is not employed. The advent of herbicide-tolerant cotton plants has greatly simplified weed management in cotton. Since the herbicides to which these crops are resistant are non-selective (e.g., glyphosate and glufosinate), weed spectrum is less a concern than growth stage. Typically, one or two herbicides are used, rather than the three or four used historically (7). There is no evidence of glyphosate-resistant weeds in Florida to this point (8).

In Florida cotton requires about 155 days of growth from planting to harvest. Important management decisions have to be made throughout the growing season, and decisions about defoliation and boll opening can affect quality and storage time if the crop is put into modules. Stain from poorly defoliated plants or regrowth and moisture from the green tissue cause the greatest loss in quality.

Experience with harvest aids (boll openers, regrowth retardants, desiccants, and mature and juvenile foliage removal) has shown that timing of the defoliant should be based on yield potential and quality of the mature, unopened bolls along with consideration of the potential yield and fiber loss of the bolls that are already open. The largest bolls are generally those set early and low, nearest the main stem on the plant. Where fruiting was hindered by early insect damage, wait as long as possible to allow the top crop to develop. A crop that set and retained most of the early fruit may be ready for defoliation when bolls are half open (16).

Where large acreage has to be harvested, growers may sacrifice some of the more immature bolls that contribute little to the final yield so that harvest can begin before adverse weather conditions reduce overall yield and quality of the crop. Bolls set in mid-summer are usually larger and will mature in 40-50 days. Bolls set in August can take 60 days or longer to mature and often contribute little to final yield if the crop had a normal fruiting season. The late flowers look attractive and may give the appearance of adding to the final yield of the crop, but should not be given preference over the fruit that was set during the first three-to-four weeks of bloom. Fruit set during the first four weeks of bloom normally contributes 90 - 95 percent of the total yield of the cotton crop (16).

Estimating the number of mature, open bolls in the field is helpful in scheduling the defoliant and boll opener. Under good growing conditions, 10 mature bolls per foot of row will produce a bale of cotton. More bolls will be needed if they are higher on the plant, and less will be needed if they are lower on the plant. Counts should include the following: (1) open bolls, including cracked bolls; (2) green bolls that are mature and string out when cut with a knife; and (3) immature bolls that are harvestable or will mature while conditions are favorable (16).

Where large acreage is to be harvested, the crop should be defoliated in stages. Harvest aids should be applied approximately 12-14 days ahead of picking. A four-row picker can pick about 40 acres a day in the early part of the season, but will pick less later in the season due to shorter days (16).

Chemical Control

All Florida cotton is glyphosate tolerant although a third to half of the growers use some other type of material for early season weed control or when specific weeds become problematic. Pendimethalin, trifluralin, and pyrithiobac are popular choices for early-season weed control (8,15).

A number of herbicides are labeled for use on cotton grown in Florida, including the following: bromoxynil (GM cotton no longer available), carfentrazone, clethodim, clomazone, dacthal, dicamba, diuron, EPTC, fenoxaprop, fluazifop, flumioxazin, fluometuron, glufosinate (GM cotton), glyphosate (GM cotton), lactofen, linuron, metolachlor, MSMA, norflurazon, oxyfluorfen, paraquat, pelargonic acid, pendimethalin, prometryn, pyraflufen, pyrithiobac, quizalofop, sethoxydim, thifensulfuron, tribenuron, trifloxysulfuron, and trifluralin.

Materials that act as plant-growth regulators (defoliant, desiccant, or boll ripener) include the following: Bacillus cereus, chlorate, cyclanilide, diuron, endothall, ethephon, ethylene, gibberellic acid, IBA, kinetin, MCDS, mepiquat, pyraflufen, thidiazuron, and tribufos.

Regional use data reflect growth-regulator use by all growers, including materials such as the following: Bacillus cereus, cyclanilide, diuron, ethephon, mepiquat, thidiazuron, and tribufos (15).

Disease Management

Disease Pathogens

In cotton grown in the southeastern United States, disease and use of fungicide has historically been low. However, Florida cotton growers have been facing increasing pressure in the form of cotton hardlock, a condition in which the fiber does not fluff out as the boll opens at maturity, but, instead, looks like wedges of an orange when broken apart. Although the quality of the cotton fiber in plants affected by hardlock may not be severely damaged by the disease, conventional spindle harvesting equipment is not able to capture the fiber and bring it into the harvester. The hardlocked cotton is knocked from the plant and falls to the ground or is strung out of the boll, giving the appearance of poor harvesting procedures (17).

Hardlock of cotton seriously affects yield in many areas of the southeastern United States and can be devastating in the Florida Panhandle. In 2002 cotton hardlock caused more than $20,000,000 in lost yield, reducing Florida's average yield from 650 lb/acre to less than 400 lb/acre (17).

Hardlock is associated with high nitrogen, high plant density, high temperature and humidity, insect damage, and seed rot. Because bolls affected by hardlock are not harvested by conventional pickers, farmers will not even attempt to harvest some fields with severe hardlock. Studies indicate that the quality of the fiber is adequate in affected plants, but attempting to “scrap” the field by running the picker a second time to get the hardlock cotton often results in little lint and increased trash at the gin and discounted cotton (17).

Hardlock is differentiated from the traditional boll rots. Boll rots — a condition in which the carpel turns brown or black and never opens — usually result from insect damage or pathogen activity after the bolls have opened or early in the season. Boll rots occur during wet weather, when the cotton boll or fiber is colonized by a number of pathogens. However, only a few fungi are responsible for the majority of infections. These fungi include the following: Alternaria gossypina, Curvularia spp., Diplodia gossypina, Helmithosporium gossypii, Fusarium spp., and Phomopsis (17).

Florida researchers have shown that the majority of hardlock is caused by the fungal pathogen Fusarium verticillioides, also known as F. moniliforme. This is the same organism that causes corn-ear rot. The main route of infection is through the cotton flowers, and fungicides applied to the flowers will control the disease (17).

Means of Control

Chemical Control

Currently, approximately a third of Florida cotton growers use a fungicide (pyraclostrobin) to control hardlock. However, all of the cotton seed planted is treated – often with a combination of fungicides – for management during emergence and early growth. Fungicides used in seed treatments include the following: azoxystrobin, carboxin, chloroneb, difenoconazole, fenamidone (in furrow), fludioxonil, ipconazole, maneb, mefenoxam, myclobutanil, PCNB, TCMTB, thiram, and triadimenol. Additionally, coppers, etridiazole, mancozeb, and phosphite are registered in Florida for disease control in cotton.

Biological Control

Bacillus subtilis is registered for use in this crop in Florida

Nematode Management

Nematode Pests

Plant-parasitic nematodes are microscopic roundworms found in soils. Nematodes attack plant roots. General signs of nematode damage include the following: stunting, premature wilting, leaf yellowing, root malformation, and related symptoms characteristic of nutrient deficiencies. Stunting and poor stand development tend to occur in patches throughout the field as a result of the irregular distribution of nematodes within the soil.

The nematode pests of cotton in Florida are the cotton root-knot nematode (Meloidogyne incognita race 3), the reniform nematode (Rotylenchulus reniformis), and the sting nematode (Belonolaimus longicaudatus). These nematodes annually cause major losses in Florida cotton production. In addition, these nematodes are important for increasing the incidence and severity of Fusarium wilt on cotton. Though root-knot nematodes may be found in all soils where cotton is grown, reniform nematodes are found mostly in fine-textured soil with less than 80 percent sand. Sting nematodes are essentially confined to soils with more than 80 percent sand.

Root-knot nematodes are known to infest at least 60 percent of cotton fields in the Florida Panhandle, and the incidence of reniform nematode is approximately 50 percent in the same area. The incidence of sting nematode in this region is not clearly known, but this nematode is more likely to be found with cotton when it is grown in the deep sandy soils of Florida. Cotton-field infestations of more than one of the problem nematodes, particularly root-knot and reniform nematodes, are common (18).

Chemical Control

About half of the Florida cotton acreage is treated for nematodes, either in the form of a seed treatment or soil treatment, and seed treatments are increasingly popular (14). Commonly used compounds for seed treatment are Aldicarb, dichloropropene, oxamyl. Dried solids of Myrothecium verrucaria are registered for soil and/or foliar treatment.

Contact

Mark Mossler is a doctor of plant medicine in the Agronomy Department's Pesticide Information Office at the Institute of Food and Agricultural Sciences, University of Florida. He provides information on pest management and pesticides to the public and to governmental agencies. Dr. Mossler can be reached at UF/IFAS PIO, Box 110710, Gainesville, FL 32611, (352) 392 4721, plantdoc@ufl.edu.

References

  1. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. 2007 Census of Agriculture: National, State and County Tables. National Agricultural Statistics Service. Washington, D.C.

  2. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. Quick Stats (Crops) Florida cotton price per unit & value of production. National Agricultural Statistics Service. Washington, D.C.

  3. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. Quick Stats (Crops) Florida cotton planted, harvested, yield, production. National Agricultural Statistics Service. Washington, D.C.

  4. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. Crop Production 2008 Summary. National Agricultural Statistics Service. Washington, D.C.

  5. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. Quick Stats (Crops) U.S. cotton planted, harvested, yield, production, price, value of production. National Agricultural Statistics Service. Washington, D.C.

  6. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2008. Florida cotton county estimates. National Agricultural Statistics Service. Washington, D.C.

  7. Aerts, M.J., Sprenkel, R.K., and Nesheim, O.N. 1998. Cotton Integrated Pest Management and Pesticide Use Survey for Florida in 1996. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

  8. Personal communication, Dr. B.J. Brecke, June, 2009.

  9. Personal communication, Dr. D.L. Wright, June, 2009.

  10. Personal communication, Dr. J.J. Marois, June 2009.

  11. Capinera, J.L. 2007. Melon Aphid or Cotton Aphid, Aphis gossypii, Glover (Insecta: Hemiptera: Aphididae). EDIS Publication EENY-173, http://edis.ifas.ufl.edu/IN330. Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

  12. Dixon, W.N. and Fasulo, T.R. 2006. Tarnished Plant Bug, Lygus lineolaris (Palisot de Beauvois) (Insecta: Hemiptera: Miridae). EDIS Publication EENY-245, http://edis.ifas.ufl.edu/IN513. Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

  13. Dixon, W.N. 2008. Whitefringed Beetles, Naupactus (= Graphognathus) spp. (Insecta: Coleoptera: Curculionidae). EDIS Publication EENY-294, http://edis.ifas.ufl.edu/in572. Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

  14. Personal communication, Dr. J.R. Rich, June, 2009.

  15. U.S. Dept. of Agriculture/National Agricultural Statistics Service. 2009. Chemical use data, cotton. National Agricultural Statistics Service. Wasington, D.C.

  16. Wright, D.L. and Brecke, B.J. 2006. 2006 Cotton Defoliation and Harvest Guide. EDIS Publication SS-AGR-181, http://edis.ifas.ufl.edu/AG188. Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

  17. Anon. 2009. Cotton Hardlock - Program of North Florida Research and Education Center. Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

  18. Rich, J.R. and Kinloch, R.A. 2005. Cotton Nematode Management. EDIS Publication ENY-004, http://edis.ifas.ufl.edu/NG015. Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Gainesville, FL.

Footnotes

1.

This document is PI220, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date September 2009. Reviewed March 2013. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Mark A. Mossler, doctor of plant medicine, Agronomy Department, Pesticide Information Office, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.