June Planted Corn

June is supposed to be dairy month, not corn planting month. However, sometimes Mother Nature prefers to combine the two. In such situations, it's important to understand the potential and limitations of June-planted corn. If the intent is to harvest dry grain, planting anything greater than an 85 relative maturity (RM) hybrid after June 1 carries a high risk. After about June 10, planting with the intent of harvesting dry grain is strongly discouraged. At that point, planting soybeans is clearly the better decision. Making late planting decisions is not easy. It often comes down to an individual’s desire to accept risk.

There is some good news along the lines of late planting and hybrid RM. Researchers in some states have found that it takes less GDU’s to reach black layer when a hybrid is planted late. For example, Purdue agronomists estimate that a typical corn hybrid's GDU requirements decrease about five GDU’s per day of delayed planting from late April - early May through at least the early part of June. This means that a 30 day delay in planting may result in a hybrid maturing in 150 fewer GDU’s (30 days times 5 GDU’s per day).

Harvesting grain and harvesting high grain yields are very different. It’s been well documented that late planted corn will yield less than early planted corn. How much less yield will depend factors such as GDU accumulation, hybrid planted, and fall frost date. In Wisconsin, yields of corn planted in early June decreases at a rate of 3% per day delay. Planting corn for silage or high moisture grain offers at least some late planting risk reduction. However, some of the same rules and principles apply. On-going studies in Wisconsin have been conducted to assess the yield and quality penalty for late-planted corn harvested as silage. In corn silage, a key feed quality factor is the ratio of grain to stover. Less grain yield usually lowers silage quality. Similar to grain, corn silage yields decrease with later planting dates. Wisconsin studies show that corn silage yield from June 10 planting dates is about 30 percent lower than earlier planting dates in May and April. By the end of June, yield levels are less than 50% of the maximum yields obtained in early May.

Cattail in Corn

Chris Boerboom, UW-Extension Weed Management Specialist, reminds us that last year's monsoon weather spawned a new weed to many corn fields......cattails. Where possible, tillage will be an effective first step in controlling cattail. Cattail is also listed on most glyphosate labels but recommendations are for high rates and when the plant is at the early heading stage. Although the rate and timing may prove challenging to incorporate into standard application programs, glyphosate may still be the best alternative (especially in no-till corn) to help mitigate cattail. Dicamba-based herbicides (e.g. Banvel, Clarity, and Status) will also offer suppression alone or when tank mixed with glyphosate. Chris Boerboom offers these cattail facts:
• Broadleaf cattail (Typha latifolia) is a native plant, but narrowleaf cattail was introduced. Both narrowleaf cattail and the hybrid of these two cattails are considered unwanted invasive weeds.
• Cattails reproduce by seed and tubers, but rapid spread is through wind-borne seed.
• Cattails can produce 20,000 to 700,000 seeds per flowering “spike”.
• Cattail seed readily germinates to start new seedlings or seed can persist in the soil for long periods of time if conditions are not proper for germination.
• If you pull cattail out of the soil and give them a toss, they always land on their root (this one is actually an observation from Rankin).

Herbicide Labels

It’s that time of year again when spraying crop fields with a herbicide is a common and necessary occurrence. If you’re a crop producer who maintains your private pesticide applicator certification, you know that a portion of that program is spent talking about pesticide labels. Pesticide labels are the written “instructions” that come along with every product. However, what makes the label different from the instructions that come along with a toaster is that pesticide labels are legally binding documents. That is, applications made outside of label recommendations are considered a violation of the law and make you subject to fines and/or penalty. The only exception is when application rates are made below the label recommended rates.

The ramifications of not following label instructions depend on the part of the label not being followed. If crop rotation restrictions are ignored there may be crop injury and/or unacceptable levels of pesticide residue in the subsequent crop or feed. The latter may occur even though no crop injury is visible.

Pesticide-related complaints are handled by the Department of Agriculture, Trade, and Consumer Protection (DATCP). The regional DATCP field representative investigates every complaint to confirm its legitimacy. Typically the first thing that is done is to insure the application was made in accordance with label instructions. This includes rate, target crop and pest, and wind speed. Yes, applying a pesticide on a day when wind speeds are above the label recommendation is a violation of the law. If the application was counter to the label, you may get lucky and only be slapped with a fine. If you’re unlucky, the person filing the complaint will get the law firm of Screwy, Dewey, and Louie (or some other) involved. Even if the pesticide application is made in accordance with the label, any off target movement is considered in violation of the law.