C.O.R.N. Newsletter: 2014-12
Potential for Spring Insect PestsAuthor(s): Andy Michel
As we gear up for planting this week and next there are two insect pests that need to be on our radar. First, reports from Purdue, Penn State and elsewhere have noticed significant flights in black cutworm. This is a migrating moth that lays eggs in corn, which can cause severe cutting of the plant. Stand loss of corn is generally associated with below-ground feeding injury, which occurs below the growing point. Although it is difficult to predict which fields will have cutworms, fields with significant ground cover and weed presence tend to be more infested. This is not a widespread pest in Ohio, and most infestations are light if we have them—although there are usually a few fields every year that we can find heavy populations. Preventative treatment for black cutworms is difficult, even with insecticidal seed treatments, but rescue treatments work well if needed. As we get planting and watch for corn emergence, the best management tactic will be to scout for cutting after corn emergence. More information can be found in our black cutworm fact sheet (http://ohioline.osu.edu/ent-fact/pdf/0035.pdf).
The other pest to watch out for is seedcorn maggot, which can feed on both corn and soybean. Like black cutworm, this is a spotty pest in Ohio, but tends to be found in fields heavy in organic matter or fields with plant material that is recently tilled under (alfalfa, hay, wheat, etc.). Unlike black cutworm, seed corn maggots are controlled quite well with insecticidal seed treatments. Alternatively, there are a number of commercially-applied, insecticide seed treatments for both crops. A final option could be to delay planting at least 3-4 weeks in a field that has had green cover tilled under—by this time most maggots would have completed larval development and damage should be limited.
Yes, this is a repeat: Temperatures are still cool
Soil temperatures from around the state are finally approaching optimum planning but still on the cool side for soybean. From the weather stations at the branches, these are the soil temperatures at 2.5 inches, from April 20 and on May 4:
County Research Branch Temperature (F) April Temperature (F) May 4
Jackson Jackson 51.1 55.9
Noble Eastern 51.8 55.6
Piketon Piketon 49.3 54.2
Clark Western 50.6 54.2
Huron Muck Crops 45.5 52.8
Ashtabula Ashtabula 32.1 49.9
Sandusky North Central 47.0 52.2
Wood Northwest 40.8 51.8
Wayne OARDC, Wooster -- 56.0
Before heading to the field, consider the conditions you will be planting into. Soybean germination begins when soil temperatures reach 50°F and moisture is present at the planting depth of 1-1.5 inches. In these conditions, emergence can typically be expected 2-3 weeks after planting. Do not plant early if the soil is excessively cold or wet. Slower germination and compaction can negate the benefits of the earlier planting date. Soybean yield tends to decrease when planting after May 10; however, any benefits of earlier planting may not be realized if soil conditions are not adequate (too wet/too cold).
I’m an optimist…So, keep in mind soybeans are an incredibly flexible crop. In 2011, only 4% of the Ohio soybean acres were planted by May 22. Last year, 45% of the soybean acres were planted by May 19. However, the state average soybean yield in 2011 was only 1 bushel/acre less compared to 2013. Clearly, the weather in the remainder of the growing season is also important.
Don’t wait to monitor stands
Believe it or not parts of the state have significant amounts of corn and soybean planted. With our “shortened” spring it is going to be very important to assess fields and your seed treatments as soon as possible. Target those fields that receive 3 or more inches of rain and dig in the rows to find the seed. If the seedlings have beautiful white roots gently replant them. However, if the seedlings have areas on the root or hypocotyl that are soft brown, tan to dark brown; they are not going to make it. Corn and soybean are vulnerable to a number of seedling pathogens.
Pythium spp. We have identified more than 25 different species of Pythium that are highly pathogenic on both corn and soybean. Interestingly or puzzling is the fact that each of the seed treatments for Pythium are not effective towards all of these species (metalaxyl or strobilurin). If you do have stand failure it is important to reexamine the seed treatment and be sure to have a good mix and higher rates of products.
We have two Phytophthora’s in the state, P. sojaefor soybean andP. sansomeana which infect both corn and soybean.
Finally, Rhizoctonia and Fusarium spp., particularlyFusarium graminearum can also infect young seedlings of both corn and soybean. We have observed F. graminearum most often in fields with a lot of corn residue.
As part of a regional study, we are collecting samples of seedlings with these symptoms of seedling blight and damping-off. Place seedlings in a plastic bag – no extra water and no paper towel. Put it in a box that won’t get crushed during mailing and ship to:
Soybean Pathology Lab, The Ohio State University/OARDC, 1680 Madison Ave., Wooster, OH 44691
Reminders about Palmer amaranthAuthor(s): Mark Loux
We spent most of the winter meeting circuit trying to put the fear of (insert deity of your choice here) in everyone about Palmer amaranth. We appear at this time to have fewer infestations of Palmer amaranth than our neighbors to the north and west, and it is our goal to keep it that way as much as possible. Some reminders about the Palmer amaranth situation:
1. Most of the nine infestations we know about are limited to small areas of individual fields at this point. The exception is an area between Jeffersonville and Midway where Palmer can be found in several fields within the area. Our assessment of that area following last fall’s preharvest scouting is that several fields will have substantial infestations this year. If Palmer is not adequately controlled in this area in 2014, the number of infested fields will increase across a larger geographic area, and the severity of the infestations will continue to increase.
2. Residual herbicides are an important component of Palmer amaranth management programs, and so by extension are also important for prevention of new infestations. They will at least control Palmer for the first part of the growing season, reducing the number of plants that have to be controlled with POST herbicides, and ultimately minimizing seed production and the risk of spread. We have ratings of residual herbicide effectiveness on Palmer in the current “Weed Control Guide for Ohio and Indiana”.
3. We have screened only a few Palmer amaranth populations for their sensitivity to herbicides. One population in far southern Ohio is resistant to glyphosate and ALS-inhibiting (group 2) herbicides. Several other populations had variable response to herbicides, showing resistance to glyphosate, ALS inhibitors, or Flexstar (PPO inhibitors - group 14) depending upon the population. So the good news is that POST glyphosate applications can still possibly control some populations of palmer amaranth. The bad news is that these populations will likely become glyphosate-resistant where management relies on glyphosate as a primary tool.
4. Take some time now to review the Palmer amaranth identification resources that are available at our website (http://u.osu.edu/osuweeds/super-weeds/palmer-amaranth/). Where the presence of Palmer amaranth is suspected this summer, contact us and send photos or plants to get help with identification.
5. Where Palmer amaranth infestations are discovered in crop fields mid-season, we cannot emphasize enough the importance of removal and destruction of plants prior to the development of mature seed. Plants should be cut off below ground, removed from the field, and burned or composted. Remediation of established infestations of Palmer amaranth is difficult and expensive, and these steps are essential to ensure that farm profitability is not reduced by this weed.
6. The two sources of Palmer amaranth infestations in Ohio have been: a) contaminated cotton feed products that originate in the south, for use as animal feed here; and b) contaminated seed used for CREP and wildlife seedlings, which originated from points west such as Kansas and Texas. So extra scouting for Palmer may be merited in fields where manure has been spread from animal operations feeding cotton feed products, and also in recent areas where cover has been established for CREP, wildlife, or similar purposes.
7. Seed to be used for any new CREP, wildlife area, or similar seeding can be tested by ODA for the presence of Palmer amaranth and other weed seed. There is no charge for this testing, but the process requires an ODA representative to come to the site of seed storage and take an official sample (rather than sending seed directly to ODA). Contact David Simmons at ODA for more information at 614-728-6410 or firstname.lastname@example.org.
New OSU Weed Management Website/blogAuthor(s): Mark Loux
The OSU field crops weed management group has transitioned to a new website,http://u.osu.edu/osuweeds. The new site is still a work in progress, but most of the important information and links are there. We would encourage you to check out and bookmark the new site, which is mobile device friendly. The site is also a blog where we hope to post fairly often with news items, new label information, photos and videos from the field, etc. Feel free to subscribe (on right lower side of main page), which results in notification of new blog entries via email. There is a direct link to submit questions and it’s also possible to do this via the comment section of the blog. Suggestions on content/format are always welcome.
Weather UpdateMay began cooler and wetter than normal as expected. The week of May 5 will start cool but then starting May 7 we will turn warmer than normal. Temperatures will reach into the 70s north and 80s south by Wednesday and Thursday. Outside of scattered light showers and a few thunderstorms, rainfall will be quite limited through Thursday which should allow ground work to resume this week.As we reach May 9-12, rain chances will increase with a storm system yielding slightly above normal temperatures with above normal rainfall.
The 8-14-day temperature outlook can be found here:http://www.cpc.ncep.noaa.gov/products/predictions/814day/814temp.new.gif
All indications are an El Nino may be forming in the Pacific Ocean. Based on years similar to Pacific Ocean water temperatures from this past winter to present and what is expected, the years closest to these include 1963, 1968, 1979, 1982, 1986 and 1997. The results for crop yields for corn were 5% above trend line, soybeans 6% above trend line and wheat 5% below trend line which are not much different than the best 3 analog years to this past winter. The bottom line is the climate patterns suggest decent yields this year but not as good as 2013 or as bad as 2012 but still likely above trend like except for wheat.
Crop Observation and Recommendation Network
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
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