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Tift County Extension Producer Updates

Cotton Notes 2021

  • Year in Review:
    • Avg Yield – 887lbs
    • Staple – 37.10, Highest Georgia avg ever (from OVT Trials)
    • Uniformity – 81.4 (from OVT Trials)
    • Seed Coat Fragments – 40.6% (Big issue this year)
      • About a 4-5 cent discount
      • Cottonseed wall has broken off and attached to fibers
      • Difficult for gin to remove, machines are designed to preserve lint not to remove fragments
      • Possibly weather-related
      • No correlation found to a specific cotton variety
      • Potential causes:
        • Seed sprouts – seed sprouts in the boll
        • Wet seed at gin –  lint dries faster than seed so cotton may be harvested when lint is dry but the seed is still wet
        • Wetting and drying of seed in the field – seed takes up moisture in times of high humidity and will shrink and expand as it drys. Multiple events of seeds wetting and drying in the field, make the seed coat weak and can easily break. – Most possible cause
  • Cotton Varieties:
    • Overall Variety Top 5: (Dryland & Irrigated)
      • DG 3799 – 74% above the trial average
      • DP 2038 – 83% above the trial average
      • DG 3615 – 65% above the trial average
      • ST 4990 – 65% above the trial average
      • DP 2055 – 65% above the trial average
  • Fruit Shed:
    • Sensitivity to fruit shed
      • Highest – from bloom to small boll
      • Lowest -14 days after bloom
    • Insects cause damage which leads to fruit shed
      • Ethylene production is in response to injury
    • Light
      • Low light (3 consecutive days) in the early fruit stage can cause shed
      • As fruit ages, light sensitivity lessens
    • Temperature
      • Fruit is sensitive to high temperature
        • High temperature accelerates development
        • Night temperatures in the 80s tend to promote shed
          • As temperature increase so does respiration
            • Doubling the burning of carbohydrates. 
            • Makes plant shed bolls
    • Percent retention of fruit on the plant. (Odd that the 2nd and 3rd numbers are low but it is an average of the entire plant)
      • 1st position – 73%
      • 2nd position  – 25%
      • 3rd position – 2%
    • The plant will abort bolls if the growth rate is too high
    • 60% of fruit shed is not uncommon
  • Precision Ag Technologies:
    • Fertilization
      • Grid vs Zone Sampling
        • Grid – no field history
        • Zone – field history known
      • Streaking
        • Any spread past 70ft reduces coverage efficiency
        • Calibrate spreaders
      • Planting
        • Seeding rate – 2-3 seed/ft
          • Speed tubes –  improved seed delivery, enables high speed planting 8-10 mph. 
        • Dept – 0.5-1.0”
          • Variability among row units is very common
          • Adjust depth and downforce to minimize variations 
          • Downforce varies from field to field
          • Large seeded variety can handle a little downforce variation
          • Small seeded varieties are very sensitive to downforce variations
        • Have seed meters tested every year
        • Aim for 98-100% singulation
        • John Deere standard vacuum pressure should be 8-10 psi, more will reduce singulation percentage
      • Spraying
        • Rate controllers will greatly help your efficiency, they keep spray rate constant when you speed up or slow down. 
      • Yield Monitor
        • Calibrate yearly
        • Better understand variability within the field for site-specific management
  • Irrigation:
    • Rooting depth is key to water availability 
    • Sandy loam – avg, 1 in/ft soil water holding capacity
    • Ex: If 3” of rain in an hour, with a 1 in/ft soil water holding capacity. A plant with a rooting depth of 1ft only has access to 1” of water. 
    • Make sure you’re getting the right flow from your pivot, in several instances, this year across the state people were watering half of what they thought they were. 
      • Especially if you are expanding irrigated acres.
    • Avg cost – $8.50/acre inch
      • $7/ac – electric
      • $12/ac – diesel
    • Peak water usage – first flower to first open boll
    • You can over water cotton
      • Managing water efficiency through water sensors has proven to minimize water stress on plants
  • Disease:
    • We can fix
      • Nematodes (once you close the furrow is over for the season)
        • Telone – about $75/3gal/ac
        • Velum – 6.5-6.8 fl oz/A (Velum Total is changing to Velum, the imidacloprid will be taken out) 
        • Propulse
        • Aglogic – 5-7lbs
        • Variety- about $3/ac more
          • Lots to consider here, I have yield and gall data we can look at
        • Seed treatments
        • Target Spot
          • Lots of options
            • Priaxor
            • MiravisTop
            • Spray by 1st week of bloom, by 6th week, should have it covered
        • Areolate Mildew
        • If you’re within 4 weeks of defoliation you’re ok
        • If more than 4 weeks out a spray is needed 
        • Fusarium
  • We have a hard time fixing
    • Boll Rot
      • Skip row?
      • Severe this past year
      • 5 types
        • Phytophthora
        • Diplodia-dark black sooty – most popular
        • Colletotrichum
        • Sclerotium rolfsii – causes white mold on peanuts
        • Bacterial
      • Can’t take them out
      • Weather-related
      • Avoid keeping leaves wet
    • Bacterial Blight
      • Variety resistance is the only shot we have
    • CLRDV
      • It’s out there
      • In some places, its bad but those have been very few
  • Fertilization:
    • pH is key
    • Grid/Zone sample
    • If you fertilize with one rate – the strong get weak and the weak get weaker
    • Once you notice potassium deficiency symptoms your time is limited before it gets severe.
    • Foliar feed Potassium
      • Catch it early – 5lbs K2O/A early bloom
      • Tricky but cotton usually responds
    • If soil is loaded with Calcium the Potassium doesn’t have anything to bind to which makes it more leachable
    • Cotton following small grain cover crop
      • Increase N by 25%
  • Insects:
    • Use at plant insecticide on every acre for thrips (in order of efficacy)
      • Aglogic
      • Imidacloprid
      • Acephate
      • Imidacloprid seed treatment
    • Supplemental foliar spray
      • Acephate
      • Bidrin
      • Dimethoate
    • The best we can do for aphids is 90%, we’ll never get them all (in order of efficacy)
      • Transform
      • Assail
      • Carbine
      • Sefina
      • Admire Pro
    • Aphids vector CLRDV
    • Plant bug sprays disrupt beneficial insects
    • You lose on average, 81 lb/a for each week you are late with a whitefly spray
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