Fall applied atrazine
By David G. Hallauer
Meadowlark District Extension Agent, crops and soils/horticulture
Some people really like the look of purple covered fields in the early spring. Most crop producers, on the other hand, aren't real fond of henbit covered fields. The solution might come this fall if you have the chance, in the form of a herbicide program.
Atrazine, for example, works really well on winter annual grasses like cheat and volunteer wheat, or winter annual broadleaves like henbit or marestail plus has some residual left for early spring germinating summer annuals. KSU research has shown that on hard to control weeds like marestail, which some herbicide programs don't touch, a tank-mix of atrazine plus 2,4-D in the fall shows enough residual to get spring germinating plants.
If you are a current user of atrazine, or want to give it a try on your difficult to control weed problems, make sure you know what it will, and won't, do. Atrazine is labeled in Kansas for fall application over wheat stubble or after fall row crop harvest anytime before Dec. 31, as long as the ground isn't frozen prior to planting corn or sorghum.
Usage rates are important. One to two pounds/acre of atrazine, usually with 1 pint/acre of 2,4-D LV4 or LV6 added, can give good burndown of most tough weeds. The two pound rate will be needed for downy brome or volunteer wheat. On broadleaves, 2,4-D seems to enhance atrazine effectiveness. The LVE formulation is a great option.
Be aware of the proper use of atrazine containing products or tank mixes. When 2,4-D is in the mix, be aware of drift considerations, though applications after fall frost have much reduced drift potential. Further, we've been granted a fall atrazine label because of our small precipitation events that tend to result in less surface water runoff. Other areas to our east aren't so lucky. Be cognizant of proper usage so we can keep this valuable product at our disposal.
To optimize foliar burn, atrazine should always be applied with either COC (when atrazine is applied alone) or with nonionic surfactant (NIS) when atrazine is tank-mixed with 2,4-D LVE. Atrazine with NIS may also be applied in nitrogen fertilizer carrier, or with paraquat (Gramoxone) herbicide, both of which further enhance foliar burn.
Time is short for your tomato crop. Nights are cooling down quickly. Our average frost date is mid-October, so even cooler temperatures are just around the corner.
Rather than let the tomatoes still left on your vines go to waste, consider harvesting them if a freeze is pending. Sure, its best to let tomatoes ripen on the vine, but they can do so off the vine if need be--provided they have reached the 'mature green stage.' 'Mature green stage' tomatoes aren't yet red, but they are mature enough to harvest. Look for full-sized tomatoes with a white, star-shaped zone at the bottom end of the fruit.
When harvesting at this stage, sort tomatoes into three groups for storage. Allocate fruit in to mostly red, just starting to turn, and those that are still green. Defects (like rots or skin breaks) should result in disposal. They're more trouble than they're worth.
Store the early picked fruit in cardboard trays or cartons, separating stacked fruit with layers of newspaper. That should help with the occasional 'leaky' fruit by preventing juice from getting to nearby or underlying fruit. Store the tomatoes until needed at 55 degrees.