iNaturalist: an app for plant ID (and other organisms)

Corn - evaluating stands, early issues

Rebecca Vittetoe and I wrote an article on evaluating corn stands, potential early issues in corn, and considerations for replanting corn. Read the article here. If you are seeing particular issues in your area, please let me know so we can leverage resources for you. I expect that anhydrous ammonia burn, herbicide injury, and uneven stands may be common this spring.

Soybeans - evaluating stands, early issues

Insect Alerts for Corn, Soybean, and Alfalfa

• Bean leaf beetles emerging but mortality expected to be high
  • Unfortunately these have been more abundant than expected so far in central Iowa - keep an eye out for them in early-planted soybean, soybean planted near alfalfa, and food-grade or other high value soybean fields.
• Seedcorn maggots in corn and soybean
  • These can be a more significant issue in cool and wet springs when the crop takes longer to emerge.
• Black cutworm alert
  • Black cutworms may be active in Iowa crop fields already.
  • The moths are highly attracted to several types of fields including those that are poorly drained, weedy, with little tillage, or with cover crops.
  • Larvae will cut plants off at the base and can often be found in the residue or soil near corn plants.
• Alfalfa weevils should be active in alfalfa fields
  • Use a sweep net to scout for larvae and adults
  • After larvae are first detected with sweeps, collect 6 alfalfa stems from 5 locations in the field (30 total) and shake each vigorously into a bucket. Inspect stems for small larvae that were not dislodged. Average number of larvae per 30 stems and use plant height to determine if the field is approaching economic threshold (Table below). Learn more here, including identification, pest biology, and management options.

Weed management challenges in a wet spring

• Spring burndowns
  • Many winter annuals have not received an early burndown application or a tillage pass to control them and prevent seed production.
  • At this point, effective management will be challenging with herbicides, but be sure to use recommended rates of AMS with burndown products, increase spray volume in fields with dense vegetation, avoid applications late in the day, and do not cut herbicide rates. If the crop is planted, be sure it is either not emerging or that the herbicides for the application allow for application to emerged crops.
• Soybeans
  • I've seen a number of soybean fields with no burndown herbicide, no spring tillage, and have heard of numerous fields that were planted and the sprayer was unable to get the preemergence herbicide on
    • It is incredibly important to get the PRE herbicides on prior to soybean emergence, because most of those residuals will cause significant injury to emerged soybeans and options are incredibly limited once the crop emerges
    • If the soybeans emerge prior to a PRE herbicide application, carefully evaluate whether the planned program will still work. If not, a POST product and a HG 15 product are likely the best choices, with the option to include fomesafen or a HG 2 product (like imazethapyr or cloransulam-methyl, etc.) for broader spectrum broadleaf residual control. 
• Corn
  • Most (but not all) corn PRE products can move to an early-POST application with ease, but be sure to check labels to make sure this is appropriate and allowed. 
  • The use of UAN as carrier with herbicide treatments to emerged corn poses a significant threat of crop injury and we advise avoiding it if the corn has emerged.
  • If corn is under significant stress from environmental conditions, applications to small weeds at low densities may be delayed until better conditions exist, but larger weeds or higher densities of weeds may pose a greater risk to the crop than the threat of herbicide injury.
• Weed control this spring
  • With the significant rainfall and sluggish crop emergence/planting, weed control may be challenging even in fields with timely herbicide applications. Scout fields diligently to check for weeds escaping residual applications.

Pesticide Container Recycling

Estimating First Crop Alfalfa Harvest with PEAQ