Common Questions Shared by Jeremy Kichler Colquitt County Agent
Thank you, Jeremy, for sharing. This is a repeat from last week but very good information shared here. Topics includes in-furrow treatments for cotton and peanut. Nitrogen applications and weed control in corn.
Thoughts on Cotton Weed Control…
BURNDOWN: Palmer amaranth must not be emerged when planting, regardless of cotton cultivar planted.
Standard programs using Valor (before Palmer emergence), Direx, and Gramoxone + Direx are advised. Dicamba or 2,4-D would be beneficial for primrose, horseweed, and radish (2,4-D is much more effective on radish). All weeds and cover crops with the exception of cereal grains should be killed at least 14 days before planting. No plant back interval exists for XtendiMax or Engenia in XtendFlex cotton; other cultivars may be planted 30 d after 1” of rainfall. No plant back interval exists for Enlist Duo or Enlist One in Enlist cotton; other cultivars may be planted 30 d after application.
Preemergence (PRE) applications: Include 2 active ingredients for better control, less crop injury, and less herbicide resistance development.
Below are some choices of preemergence treatments.
1) Brake + Reflex 2) Brake + Warrant 3) Direx + Warrant 4) Reflex + Direx 5) Reflex + Warrant
HERBICIDE RATES ASSUME TIMELY SEQUENTIAL POST APPLICATIONS AND DIRECTED LAYBY
1) Brake contains fluridone; 1 pt/A is an effective rate in mix with other herbicides. Fluridone requires significant rain/irrigation to become fully active.
2) Warrant: For most soils, 32-40 oz/A is in order. Effective on most grasses, pigweeds and is essential for spiderwort.
3) Direx: For most soils the ideal rate is 10-16 oz/A; lower rates on sands or under intense irrigation. Avoid diuron PRE if it was applied within 14 d of planting as a burndown.
4) Reflex: For most soils, ideal rate is 10-12 oz/A when in these tank mixtures. Reflex mixtures are the most effective option for
Palmer.
NOTE: Add paraquat if pigweed is emerged; a jar test is strongly advised if mixing with Brake. Seedling Diseases in Cotton… are typically more severe during cooler and wetter weather, Why? Primarily the cool, wet soils slow germination and slow growth and development of the seed and seedling. Slow germination and emergence coupled with low vigor early on gives our most important seedling disease pathogen of cotton, fungus Rhizoctonia solani, the chance to attack and cause significant stand loss. Rhizoctonia can (and does) certainly cause losses even in warmer soils, but the impact is greatest in cooler and wetter soils.
NOTE: the key here about increasing risk to seedling diseases is less about “cooler and wetter” and more about ANYTHING that slows germination and development. Other factors include 1) poor seed quality, and 2) some considerations with herbicides and possibly other things put directly in the furrow. NOTE 2: Rhizoctonia almost always causes post-emergent damping-off seedling disease. Plants come up, kind look ok, and then buckle at the knees and die, or they just stay small and fail to thrive. Dig the plants up and you should see a beautifully diagnostic lesion just below the soil line. If the plants NEVER come up, you may have Pythium (possibly especially in cooler soils) or other seedrot issues.
SO, what to do? To minimize risk to seedling diseases, 1) make sure soil temps at 4 in. are AT LEAST 65F, 2)avoid planting in cooler and wetter conditions are imminent, 3) make sure you have the best quality seed (ask conditions); smaller seed is sometimes prone to greater stand problems than is larger seed, 4) insure a good fungicide seed treatment package (most commercial seed is already treated with a combination of excellent fungicides, and 5) if you are worried about higher risk to seedling diseases, consider additional treatments.
Additional treatments for cotton include 1) additional, higher-end seed treatments, and 2) liquid in-furrow fungicide. Neither additional treatment is a “general recommendation” for me as our standard cotton seed treatments are adequate to protect stand much of the time. However, when in doubt, additional treatments are good “insurance” against seedling disease, especially use of azoxystrobin (6 fl oz/A) in-furrow against Rhizoctonia.