HARDIN COUNTY — The following articles came from the CORN Newsletter 2016-23 & 24 with the first article written by Kelley Tilmon and Andy Michel, OSU Entomologist. With continued dry weather, the pest we’ve been getting the most calls about is the spider mite. This is just a reminder that vigilant scouting for this pest is a good idea right now. It is also important to re-scout five days after treatment because many products will not kill the eggs, and populations can resurge. Any follow-up treatment should be made with a product with a different mode of action to reduce resistance development (so, for example, if you used something with bifenthrin the first time, you might switch to Lorsban the second time, or vice versa). This link will take you to the OSU publication on spider mites in soybean: http://ohioline.osu.edu/factsheet/ENT-24

There are two miticides that are newly labeled for spider mite management in soybean and/or some types of corn: Agri-Mek from Sygenta and Zeal from Valent. We at OSU have not tested these products yet, but are currently running trials with both of them in northwestern Ohio. Thanks to all of our readers who helped identify suitable locations.

Normally we only worry about spider mites in soybeans, but when conditions are just wrong they can impact corn as well. Corn that has been treated with some fungicides and insecticides (particularly a broad-spectrum pyrethroid) are more likely to experience spider mite outbreaks under hot, dry conditions. A general guide for treatment of two-spotted spider mites in corn is 15-20 percent of leaf area covered in mite colonies, with continued dry weather expected. Control is most likely to be economical from pre-tassel through soft dough, and unlikely to provide a return from dent onward. An excellent field crop entomologist Chris DiFonzo at Michigan State has put together a nice table listing spider mite products for corn, soybean, dry bean, and sugarbeet. Always check your labels.

http://msue.anr.msu.edu/news/spider_mite_spraying_in_michigan_field_crops_brand_new_cheat_sheet

From OSU Corn Specialist, Peter Thomison. Weather forecasters are calling for continued above average temperatures in August, especially higher night time temperatures. Past studies show that night time temperatures affect yield potential. High night temperatures (in the 70s or 80s degrees F) can result in wasteful respiration and a lower net amount of dry matter accumulation in plants. The rate of respiration of plants increases rapidly as the temperature increases, approximately doubling for each 13 degree F increase. With high night temperatures more of the sugars produced by photosynthesis during the day are lost; less is available to fill developing kernels, thereby lowering potential grain yield. High night time temperatures result in faster heat unit (GDD) accumulation that can lead to earlier corn maturation, whereas cool night temperatures result in slower GDD accumulation that can lengthen grain filling and promote greater dry matter accumulation and grain yields.

Research at the University of Illinois conducted back in the 1960’s indicated that corn grown at night temperatures in the mid-60s (degrees F) out yielded corn grown at temperatures in the mid-80s (degrees F). Low night temperatures during grain fill (which typically occurs in July and August) have been associated with some of our highest corn yields in Ohio. The cool night temperatures may have reduced respiration losses during grain fill and lengthened the rain fill period. Cooler than average night temperatures can also mitigate water stress and slow the development of foliar diseases and insect problems.

From OSU Wheat Specialist Laura Lindsey and Matthew Hankinson. A pdf of the 2016 Ohio Wheat Performance Test can be found at the Soybean and Small Grain website at: http://stepupsoy.osu.edu/node/35. A sortable version of the Ohio Wheat Performance Test can be found at: http://www.oardc.ohio-state.edu/wheattrials/

Test results are for 72 soft red winter wheat varieties grown at five Ohio locations (Wood, Crawford, Wayne, Darke, and Pickaway County). Variety selection should be based on disease resistance, average yield across test sites and years, winter hardiness, test weight, and standability. Overall, grain test weight averaged 58.4 lb/bu (compared to an average test weight of 56.3 lb/bu in 2015). Grain yield averaged between 97 and 119 bu/acre at the five locations.

A Putnam County Ag Tour is going to be hosted by the Putnam County Soil & Water Conservation District on Saturday, Aug. 13 starting at 7:30 a.m. with breakfast at the OSU Extension office meeting. Sites to be visited include the Putnam County Soil Health Agricultural Research Plot (SHARP) site, a Two-Stage Ditch at Bill Oedy’s farm, Vennekotter’s Swine operation and Ellerbrock and Welch Hops site. To reserve your seat, register online at https://www.surveymonkey.com/PCAgTour2016 .