By Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

Working with Bill Bamka, County Extension Educator from Burlington County NJ, UD Weed Science Program confirmed that a population of common ragweed in New Jersey is resistant to glyphosate. The long-term history of the field is not known, but the past couple of years it was planted with soybeans. Last year, the preemergence herbicides did not provide adequate control and multiple applications of glyphosate were used postemergence. This is not the first confirmation of glyphosate-resistant common ragweed in the region; but the first in New Jersey. We have no reports of common ragweed resistant to glyphosate in Delaware.

In this situation, rotating to corn and use of atrazine is the best option. When rotating back to soybeans, use no-till because germination will be less than if tillage is done. The field will need to be treated with a preemergence application of cloransulam (i.e. Sonic or Gangster) or metribuzin (Tri-Cor, Boundary, or Canopy, generics). But there will definitely be a need for a postemergence herbicide and the best options would include Blazer Ultra, Cobra, Reflex, and Liberty (with Liberty Link soybeans). If cloransulam was not used at planting, FirstRate or Permit Plus (with STS soybeans) would also be options.

Source: Read More from Weekly Crop Update

By Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

This is an article written by Dwight Lingenfelter and Bill Curran from Penn State and modified for Delaware.

As more farmers use vertical tillage to manage crop residues or to mellow the seedbed prior to planting (especially soybeans), questions have arisen about possible impacts of using these types of tillage operations in combination with certain soybean herbicides. The PPO herbicides (Group 14) in particular are drawing attention in these discussions. The soil applied PPOs include flumioxazin (Valor SX, Valor XLT, and Envive); sulfentrazone (the Authority family lineup and Sonic), fomesafen (Prefix, Reflex); and saflufenacil (Sharpen, Verdict, Optill). In general, if a vertical tillage operation is done before the PPO herbicide application, residual weed control will typically not be negatively affected. However, if the PPO herbicide was applied before the tillage operation then weed control could be compromised. In particular, flumioxazin and saflufenacil-containing herbicides can be affected the most. In this case, any tillage after herbicide application disrupts the uniform layer of herbicide potentially causing weed escapes or patchy weed control.

Source: Read More from Weekly Crop Update

By Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

I always get questions on what to use to control mornningglory in soybeans at about the time to spray postemergence. Morningglory control starts at planting with a preemergence herbicide with broadleaf products such as Canopy, Valor XLT, Envive, Fierce, Prefix, Sonic or the Authority products. These will need to be followed up with a postemergence application in a timely manner for effective control (to morningglory no larger than 3”). The preemergence herbicide slows the growth of morningglory plants and seems to “set them up” for better overall control. This has been more consistent for morningglory control than any tankmixtures or glyphosate additives that I have evaluated.

Source: Read More from Weekly Crop Update

By Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

The formulations of Lumax and Lexar have been changed to Lumax EZ and Lexar EZ. Both products still contain mesotrione, atrazine, and s-metolachlor; and in the same ratios as the old formulations. The concentration of Lexar remained the same and the use rates are the same for the Lexar EZ formulation (3 to 3.5 qts/A). Lumax EZ (3.67 SC) is less concentrated than the older version (Lumax 3.9 SC) and so the use rates are slightly higher. So, instead of using 2.5 qts of Lumax, the Lumax EZ use rate is 2.7 qts, etc.

For vegetable growers and those advising vegetable growers, be sure to read all rotational restrictions and be sure you understand them. A lot of labels address dry beans or dry peas, but do not address succulent beans or peas. Some labels provide rotational restrictions others provide rotational guidelines. I am not aware of any acetachlor-containing herbicides that permit most of our vegetables to be planted within 15 months of application. Likewise, the new products of Anthem, Fierce, and Zidua do not fit into vegetable rotations.
Source: Read More from Weekly Crop Update

All NJ licensed pesticide applicators, as well as dealers, who store pesticides are required by law to send a copy of their storage inventories with an explanatory cover letter to the local fire company by May 1st each year. [Read more…]

From Weekly Crop Update

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

All winter I have been talking about Reflex as a tool for managing Palmer amaranth and other problem weeds. Farm articles from the southern US often discuss this product as well. It is commonly used for snap beans and soybeans. But it is one of those products with unique regional restrictions. On Delmarva, we are limited to one application every two years, and a maximum use of 1.5 pts. South into the Carolinas and Georgia, they can use higher rates and use it every year. North of Delaware (Pennsylvania and New Jersey) it is limited to one application in alternate years with a maximum use rate of 1.25 pts. So be sure to plan your herbicide rotation accordingly.

Source: Weekly Crop Update