Extension Crop Rpt 7-2-15

Extension Crop Rpt 7-2-15

Extension Crop Report June 30 - July 2

Northern corn leaf blight and soybean defoliation
(L) Northern corn leaf blight and (R) soybean defoliation caused by insect feeding.

Nathan Mueller, Cropping Systems Extension Educator for Dodge and Washington Counties: Most corn is between the V6 and V12 growth stages. Growers, seed companies, and agronomists are monitoring northern corn leaf blight in the area as lesions are now visible. Scouting will be important, especially on more susceptible hybrids following corn. Corn blotch leaf miners are now active, but at low levels. Overall, corn crop condition has been improving with a slightly drier second half of June and producers have been actively fertigating. Most soybeans range from VE to R1 (beginning bloom). Insect pressure is low and has mainly been green cloverworm, which appears to be decreasing. In some fields they caused up to 10% defoliation, which would still not be economical. We're starting to see some Septoria brown spot on lower leaves of soybeans. Marestail has been more problematic this year due to later emergence, herbicide resistance, and late pre-plant herbicide applications due to the wet weather. Second cutting of alfalfa is starting and the few wheat fields in the area were hit hard by stripe rust, Fusarium head blight, and wheat stem maggot. 

Agronomic concerns for the coming week:

  1. Watch soybean growth stage limits, pre-harvest interval, and crop rotation restriction times on herbicides.
  2. Look up northern corn leaf blight ratings for all of your hybrids, scout hybrid's with weak ratings first.
  3. Evaluate herbicide program for next year based on current marestail pressure in your fields

Read more on Mueller's blog, Croptechcafe.org. (July 2, 2015)

John Wilson, Extension Educator in Burt County: We've gone from having too much rain to corn starting to curl on hotter days. Corn is about ready to tassel in early planted fields. (June 30, 2015)

Keith Jarvi, Extension Educator in Dakota, Dixon, and Thurston counties:  Corn really shot up in the last 10 days and growth is close to where it should be.  In surveying corn rootworm check plots, I found some third instars and pretty high infestations. Rootworms are expected to hit peak feeding the third week of July.

Tyler Williams, Extension Educator in Lancaster County: Corn and soybean growth stages vary widely in the county. We could use a little rain — maybe an inch — in northern Lancaster County and Cass County.  We got 8 inches of rain in early June, but nothing in the last 14 days. Looking at the forecast, next week should warm up and we might see some dry areas start to develop. (June 30)

Ron Seymour:, Extension Educator in Adams County: Conditions had been pretty wet in some areas, but are drying down and irrigation is expected to start soon. Corn is at the 8- to 12-leaf stage. Some fields have ponding and are showing signs of nitrogen deficiency. There has been a little common rust and some corn borer feeding. Soybeans are at a wide range of maturities and look tough in a lot of places. We're seeing a lot of weeds, some of which are pretty tall. Growers may have a tough time getting control when the corn is 8 inches and the weeds are already 12 inches. Pastures here look pretty good from spring rains, but need a little more water. (June 30)

Julie Peterson, Extension Entomologist at the West Central Research and Extension Center: Corn here is at the 4- to 8-leaf state. Conditions are dry again and some pivots are running; herbicides and fertilizers are being applied. We found two western bean cutworm adults in traps this week, indicating the beginning of their flight. Based on our model, in North Platte 25% of western bean cutworm emergence should occur between July 10 and July 15. (See WBC details and moth flight dates for multiple sites in this week's CropWatch story.) In continuous, no-till soybean research plots at the station, we're seeing pretty high populations of dectes stem borer, while the adjacent area in corn had none. Without crop rotation, numbers in these areas build up quickly. (June 30)

Robert Wright, Extension Entomologist: We're finding a few baby grasshoppers in field margins at the South Central Ag Lab, Clay Center. Some summer-feeding species are hatching out, but given the rains and plentiful vegetation in field margins, they should probably stay in these areas for a while. (June 30)

Keith Glewen, Extension Educator in Saunders County: Soybeans are still being replanted. Hopefully the third time is the charm.  In some cases active springs are causing water problems with replant and postemergence weed control in upland areas of eastern Nebraska. (June 30)