Community Discussions

Expert discussions for agricultural chemical professionals, crop consultants, and Texas producers on pesticide applications, weed management, and regulatory compliance.

Q: What is the best herbicide rotation for managing glyphosate-resistant waterhemp in soybeans?

Posted by SoyProducer · 43 replies

Waterhemp (Amaranthus tuberculatus) resistance to glyphosate is widespread across the Midwest and is spreading into Texas. The most effective resistance management strategy combines a pre-emergent application of a Group 14 herbicide (PPO inhibitor, e.g., flumioxazin or sulfentrazone) with a post-emergent Group 27 HPPD inhibitor (e.g., mesotrione or tembotrione). Avoid using Group 2 (ALS inhibitors) as waterhemp has developed multi-site resistance to those as well. Residual products applied at planting are essential since waterhemp germinates over an extended period.

Q: How do I calculate the correct mix ratio when diluting a 4 lb/gallon herbicide concentrate?

Posted by NewApplicator · 27 replies

For a 4 lb a.i./gallon formulation applied at 1 lb a.i./acre in 20 GPA, you need 0.25 pints per acre (1 lb a.i. ÷ 4 lb/gal = 0.25 gallons, then convert). Always calculate using the active ingredient rate on the label and work backwards to the volume of formulated product. Use a calibration formula: fluid ounces per acre = (desired a.i. rate × 128) ÷ (concentration in lb a.i./gal). For tank mixes, add products in the order: water, WDG/WP, flowables, EC, adjuvants — following the ALWAYS system (Agitate, Labels, Water, Add, Label-specified order, Stir/agitate, Yes-recheck).

Q: What fungicides are most effective for controlling gray leaf spot in corn?

Posted by CornGrowerTX · 35 replies

Gray leaf spot (Cercospora zeae-maydis) is best managed with a preventive fungicide application at tasseling (VT) through early silking (R1). Strobilurin (Group 11) + triazole (Group 3) premix products such as azoxystrobin + propiconazole or pyraclostrobin + metconazole provide excellent efficacy. Avoid relying on strobilurins alone as QoI resistance in gray leaf spot populations has been documented in several states. Scouting before the V8 growth stage helps determine whether disease pressure justifies the fungicide investment based on hybrid susceptibility ratings.

Q: What adjuvant should I use with a post-emergent grass herbicide to improve uptake?

Posted by RangeManager · 19 replies

Post-emergent grass herbicides like fluazifop (Fusilade) or sethoxydim (Poast) typically require a non-ionic surfactant (NIS) or crop oil concentrate (COC) to penetrate the grass cuticle. The label will specify — NIS is usually used at 0.25% v/v, and COC at 1% v/v (1 qt/100 gallons). Adding ammonium sulfate (AMS) at 2-4 lb/100 gallons is beneficial in hard water areas as it prevents calcium and magnesium antagonism. Never add NIS to dicamba without reading the specific label requirements to avoid off-target movement from enhanced volatility.

Q: How often should spray nozzles be replaced on agricultural application equipment?

Posted by EquipmentPro · 22 replies

Nozzle replacement frequency depends on the material they are made of and what chemicals are being applied. Stainless steel nozzles typically last 75,000–100,000 acres; ceramic nozzles can last 200,000+ acres. Nozzles should be replaced when individual output deviates more than 10% from the original flow rate, as documented by a standard catch test. Check nozzles at least every 25,000 acres for conventional crops. Pre-season calibration should be mandatory, and post-season inspection helps identify erosion patterns from abrasive tank mixes.

Q: What is the difference between a systemic and a contact insecticide?

Posted by AgStudent · 14 replies

Contact insecticides kill insects only when the chemical touches them directly — they do not move through plant tissue. Examples include pyrethroids (permethrin, lambda-cyhalothrin) and organophosphates. Systemic insecticides are absorbed by the plant and move through the vascular system, making all plant tissue toxic to feeding insects. Neonicotinoids (imidacloprid, thiamethoxam) and Group 4A products are classic systemics. For piercing-sucking insects like aphids and whiteflies hidden under leaves, systemics are generally more effective; for chewing insects on leaf surfaces, contact products may suffice.

Q: How do I dispose of empty pesticide containers properly in Texas?

Posted by GreenApplicator · 31 replies

In Texas, empty pesticide containers must be triple-rinsed or pressure-rinsed before disposal. Rinsate should be added to the spray tank, not dumped on the ground or down a drain. After rinsing, puncture the container to prevent reuse and dispose of it as solid waste — most properly rinsed containers can go in regular landfill under EPA guidelines. Texas TDA and EPA operate the CleanScape program in some counties for free container recycling events. Never burn pesticide containers, as incomplete combustion can release toxic compounds.

Q: What do FRAC, HRAC, and IRAC classification codes mean on pesticide labels?

Posted by LabelReader · 16 replies

FRAC (Fungicide Resistance Action Committee), HRAC (Herbicide Resistance Action Committee), and IRAC (Insecticide Resistance Action Committee) are international scientific groups that classify pesticides by their biochemical mode of action. The FRAC/HRAC/IRAC code on a label tells you what group the product belongs to — products in the same group share the same resistance mechanism. To delay resistance, rotate between products in different groups each season. For example, an HRAC Group 9 herbicide (glyphosate) should not be followed by another Group 9 product if resistance is suspected.

Q: Can I apply a herbicide the same day as planting corn?

Posted by PlantingWindow · 25 replies

Pre-plant incorporated (PPI) herbicides must be incorporated before planting as specified on the label — often 3-7 days before. Pre-emergent (PRE) herbicides are applied at or shortly after planting and before weed germination. Always read the specific label for the crop rotation restrictions, which indicate how many days after application you can plant the target crop. Applying a herbicide with an insufficient plant-back interval can result in crop injury or failure. Atrazine, for example, has a 45-day restriction before planting sensitive crops like sunflower.

Q: How do I report a pesticide spill or environmental contamination incident in Texas?

Posted by Compliance101 · 11 replies

In Texas, pesticide spills affecting soil or water must be reported to the Texas Commission on Environmental Quality (TCEQ) Spill Reporting Hotline at 1-800-832-8224 within 24 hours. Spills affecting workers must also be reported to OSHA and may trigger WPS incident reporting requirements. Contact CHEMTREC at 1-800-424-9300 for immediate technical guidance on spill response and cleanup. Document the incident thoroughly — quantity spilled, location, weather conditions, and response actions taken — as this documentation may be required by TDA or EPA during any subsequent investigation.