Cotton

Maximizing yields from today's top-performing cotton varieties starts with the development of a healthy root system.

Nematode control starts with the development of a management plan. Three practices are commonly used to effectively combat nematodes in existing fields: chemical controls, crop rotation, and postharvest tilling.

Telone® II soil fumigant is proven to reduce nematode populations and, in turn, improve lint production. Telone II moves through the soil on its own to create a zone of protection around developing roots.

Root-knot, reniform, lance and sting nematodes are the four major species of nematodes present throughout the cotton-producing states. Fusarium Wilt and Verticillium wilt are diseases that also can result in significant damage.

  • root-knot-nematodes Root-knot nematode damage in Louisiana
    Louisiana State University
    Root-knot nematodes are named for the galls, which look like knots in a rope, that they create on plant roots. These nematodes are some of the most dangerous nematodes and are found in cotton fields across the nation. The density of root-knot nematodes is typically scattered within an infested field. They can be found in nearly any field, but are most commonly found in sandy soils. The occurrence and severity of Fusarium wilt and Verticillium wilt is increased significantly in fields with root-knot nematodes. Potential host weeds: Prickly sida, smallflower morningglory, ivyleaf morningglory, bermudagrass, johnsongrass, cocklebur, goosegrass, red root pigweed, purple nutgrass, yellow nutsedge, purple nutsedge, smartweed, teaweed, lambsquarter, ground cherry, crotolaria, sicklepod
  • Reniform nematodes, the most difficult nematodes to detect, are commonly found starting from North Carolina and moving south along the Atlantic coast, across the Gulf Coast and into Texas. Reniform nematodes do not cause galls, as they feed on the outside of the roots. They can prosper and quickly reproduce in a variety of soils, and cause increased occurrence and severity of cotton-seedling diseases. Reniform densities tend to be uniform within an infected field. Typically, infestations are the result of both reniform and root-knot nematodes. Fields with a high density of reniform nematodes could cause greater than a 70 percent loss in yields. Potential host weeds: Florida beggarweed, purple nutsedge, sicklepod, smallflower morningglory, crotolaria, cocklebur, sow thistle, jimsonweed, Florida pusley, velvetleaf
  • Lance nematodes, specifically Columbia lance nematodes, are the least widespread nematode, populating several states in the southeastern United States. Lance nematodes tend to be scattered throughout an infected field and cause a stunted taproot and reduced root system. They may increase occurrence and severity of seedling diseases and Fusarium wilt. Crop rotation is not an effective management tool for lance nematodes because they thrive on a wide range of hosts. Severe infestations of lance nematodes could result in up to a 60 percent yield loss. Potential host weeds: Nutsedge, pigweed, sicklepod, henbit, crimson clover, showy crotalaria
  • Sting nematodes result in reduced root and plant growth, and the root tip often swells, causing the root to appear to be cut off. Sting nematodes prefer sandy soils and are commonly found along the Atlantic and Gulf Coasts. They cause the most damage to young plants with developing root systems, remaining in the soil and feeding on root tips. Sting nematodes generally need at least 80 percent sand content in soils to survive. Potential host weeds: Beggarweed, cockcrabgrass, cudweed, dogfennel, johnsongrass, morningglory, ragweed, wild carrot
  • Fusarium wilt quickly spreads throughout the field after infection. The fungus may attack cotton seedlings, but the disease usually appears when the plants are more mature. Affected plants are at first darker green and stunted, followed by yellowing of the leaves and loss of foliage. Symptoms first appear on lower leaves around the time of first flower. The leaf margins wilt, turn yellow and then brown while moving inward. Infected plants fruit earlier than normal with smaller bolls that open prematurely.
  • Verticillium wilt causes young plants to exhibit yellow leaves and stunting, and often death. Following the seedling stage, older plants display a chlorotic mottling on the leaf margins and between the major veins. Plants attacked during later stages of growth display a mottling on the lower leaves first, progressing toward the top of the plant as the season progresses. A single branch can often show symptoms in the early stages of disease. Yellowing progresses inward, followed by browning and death. Verticillium wilt is widespread among fields growing cotton and causes the most damage during cool and wet growing seasons.

infested-with-nematodes

A cotton field infested with nematodes commonly exhibits stunting, yellowed leaves, wilting and stress, which are caused by poor nutrition and lack of water. Nematodes trigger these symptoms by reducing the ability of the roots to uptake water and nutrients and stunting root growth.

Plant-parasitic nematodes use a hollow tube – known as a stylet – for feeding by puncturing root cells and withdrawing nutrition from the host plant. Additional symptoms can include an overall reduction in root mass, signs of galling on the roots, or distorted regions.

Above-ground symptoms
  • Severely infected plants may be stunted and may wilt under drought stress several days before noninfected plants
  • Height and size of the cotton is oftentimes reduced
  • Widespread irregular cotton plant growth
  • Chlorosis, or yellowing, is not pronounced, but plants often express nutrient deficiencies, especially nitrogen deficiency
  • Symptoms usually are first expressed in sandy areas of the field
Below-ground symptoms
  • Symptoms of some nematodes are difficult to detect as they don't cause distinct galls or swellings
  • Root-knot-nematode infection of roots results in swellings, or galls, and reduced root mass
  • The galls are typically much smaller than those observed on hosts such as soybeans, okra or other vegetables
    • Root galling results in reduced nutrient and water uptake, and premature drought stress leading to yield losses

In addition to monitoring visual symptoms,  Find a Soil Sampling Lab also is an effective method to determine the presence of nematodes

Nematode control starts with the development of a management plan. A soil sample should be conducted early on to test for nematodes. If nematodes are found, population density levels should be established. When nematodes are not present, steps should be taken to reduce the probability of introduction. Nematode sampling is difficult and results are not always 100 percent correct.

After reviewing soil samples, design and implement a successful nematode management plan that will meet the needs and goals of your operation. When nematodes are present, the goal is to keep populations from spreading to noninfested fields. Techniques to prevent spreading include isolating irrigation water and thoroughly cleaning all equipment and tools between infested and noninfested fields.

Three practices are commonly used to effectively combat nematodes in existing fields: crop rotation, postharvest tilling and chemical controls.

Crop rotation:
  • It is important to accurately identify the affecting nematode as that will dictate the appropriate rotational crop. To maximize crop rotation efficacy, establish a two-year rotation with cotton and a nonhost or poor-host crop. Crops such as corn, peanuts, sorghum, millet and other grass crops are effective rotation crops with cotton.
Postharvest tilling
  • Postharvest tilling reduces population densities by exposing nematodes to drying, therefore halting reproduction.
Chemical controls
  • Nematicides, such as TeloneĀ® II soil fumigant, are scientifically proven to reduce nematode populations and, in turn, improve lint production. Telone II is injected into the soil as a liquid and immediately converts to a gas, which creates a zone of protection around developing roots. As a fumigant, Telone II moves through the soil on its own, rather than requiring water or incorporation for movement.
  • Telone II, a preplant soil fumigant, controls all major species of nematodes. According to the University of Florida, recent research reports up to a 50 lb./A increase of lint when fields infected with root-knot nematodes are treated with Telone II and a 35 lb./A increase in fields infected with reniform nematodes.

Telone® II soil fumigant provides cotton growers with an excellent fumigation option that consistently produces great yields. Listed below are the numerous benefits of Telone II:

  • Greater efficacy compared with contact nematicides
  • Controls all major species of nematodes, including root knot, reniform, lance and sting
  • Helps manage nematode-transmitted diseases and viruses
  • Increases root efficiency for better use of water and fertilizers
  • Prepares the soil for the seed to optimize growth and production potential
  • Can be applied broadcast or in-row
  • Fuming activity allows movement throughout the soil profile
  • Labeled for at-plant application in Georgia
  • Excellent option for use in site-specific application

Application Guides

The new Telone Precision System is a closed-system unit that minimizes the number of parts that could potentially malfunction, such as motors and pumps, when growers are applying a fumigant such as Telone II. This system uses compressed nitrogen to push Telone II into the ground and acts similar to an aerosol can, which results in continual pressure flow for consistent and accurate applications.