C.O.R.N. Newsletter 2011-29

Dates Covered: 
August 30, 2011 - September 6, 2011
Editor: 
Rob Leeds

Will we have an early frost?

The next two weeks(August 30 - September 13) will feature slightly above normal temperatures and slightly below normal rainfall. This week will feature a warm up with 80s/90s for the second half of the week. The best rain chances will be later this week into early next week.

At present, all indications are for a normal frost but if we continue with the drier than normal pattern, northwest flow aloft and high pressure, there is an increased risk of earlier frost and freezes in late September or the first half of October. Drier top soils and low dewpoints allow for warm days but chilly nights in fall. We will monitor it.

Continuous soybean?  Now is the time to check those fields

Continuous soybean? Now is the time to check those fields

We don't recommend growing soybeans year-after-year in the same field. The list is endless why this is not a good thing to do, but we also know that commodity prices, planting restrictions, landlords, etc. force this option on almost 1/3 of our field crop production acreage. This production practice is less than optimal primarily due to the build-up of pathogens in either the soil or on crop residues. If pathogen populations are too high, then the losses can be very substantial. Case and point, Soybean cyst nematode (SCN), frogeye leafspot and Sclerotinia white mold. There are several cases in Ohio, where low levels of a particular disease were found in a field at the end of one growing season and the same variety was then planted back into the same field the following year, which resulted in an outbreak of disease and greatly reduced yields. The key to preventing this from happening is to go look at those fields - now. In addition, the R6 growth stage is a very key time to tell if you chose the right variety for that particular field (resistance to Sudden Death Syndrome (SDS), SCN, White mold, Stem Canker, Frogeye) as well as if the pathogen population is increasing. Road side scouting/truck scouting doesn't work in these cases, you need to wade into the field and look into the canopy. Here is some of what we have been finding for ourselves and hearing about from others.

- Soybean cyst nematode (SCN). Over the next few weeks the fields will start to mature. Where SCN populations are very high we have observed that the SCN "hot spots" will mature much faster than the rest of the field, giving it a patchy appearance. For those pockets which are maturing early, dig up the plants and check the roots for the white pearls of the SCN females. They will be the size of the head of pin. If you can easily find them, this is a good field to put wheat or corn in for 2012.

- Sudden Death Syndrome (SDS) and Brown Stem Rot (BSR). Both of these diseases have similar foliar patterns. I tend to think that SDS has a brighter yellow cast to the leaves than BSR. BSR can also give a "greasy" appearance to the base of the stem. The best way to separate these two is to compare the crown and the pith. For SDS the internal tissues of the crown are gray and sometimes the blue-green color of the spores are on the surface of the root tissue; the pith is white and healthy. In contrast, BSR, the crown is white but the pith is chocolate brown color. For BSR, this discoloration of the pith may be the whole length of the plant or just at a few nodes. Soil pH plays a key role in symptom development for BSR, so that is something else to make note of. SCN also plays a role in the severity of the symptoms for SDS, again check those roots for signs of the SCN females.

- Frogeye leaf spot. This foliar disease has become established in Ohio and successfully overwintered again in 2011. Inoculum levels were low but it is present in a few fields in Ohio. Check the mid and upper canopies for this disease, if present; change to a variety with higher levels of resistance or switch to wheat or corn in 2012.

- Sclerotinia stem rot. Plants with this will begin to appear in those locations that had cool nights and closed canopy during flowering. I found the first plant last week, with a lesion near the base of the plant, the plants will stand tall with the leaves withered and thick cottony growth on the main or side branches. There are some fields that get this disease every year, these fields are always best to rotate to prevent buildup of inoculum to too high a level. Under no-till conditions, sclerotia (the survival structures) will break down on the soil surface faster than if they are buried.

- Phytophthora stem canker can actually be found throughout the year, approximately 1 to 2 weeks after a heavy rain. As you are walking through the fields, if you find scattered dead plants or those that are wilted with a chocolate brown canker colonizing the stem, that plant was killed by Phytophthora sojae. For 2012 choose a variety with a higher level of field resistance or partial resistance. The Rps genes are still important, but they no longer provide full protection across a field.

By taking the time to check fields now, to see what is happening in a given field will help you make better decisions on variety selection as well as what to plant in that field in 2012. For images of these diseases and for more information on all Soybean diseases vist the Plant Pathology, Ohio field crop diseases website at 
http://oardc.osu.edu/ohiofieldcropdisease/t01_pageview2/Home.htm

Stink Bugs on Soybeans

Stink Bugs on Soybeans

Last May we wrote an article that discussed potential concerns with stink bugs this summer and in coming years. We are especially worried about the brown marmorated stink bug, an invasive stink bug moving toward Ohio from the Mid-Atlantic States. Reports from that region are that the brown marmorated stink bug is again causing injury to soybeans at this time.

Currently, no reports of this stink bug on soybeans in Ohio are being received. However, because of the potential for injury, we need to keep our eyes on it. A fact sheet on the brown marmorated stink bug can be found at http://entomology.osu.edu/ag/images/Marmorated_Stink_Bug.pdf. Also, because of our general concern of more problems with other stink bugs, especially green stink bugs on soybeans, we feel it also warrants our attention. We have recently placed photos of the various stink bugs on our web site, including a group shot to show them together showing their relative size difference. These can be seen at http://entomology.osu.edu/ag/pageview3.asp?id=1152.

During the next months as soybeans finish pod fill and begin to mature, growers might want to check their fields for a higher abundance in stink bugs than normal. This is especially true in southern OH where the green stink bug might be occurring in higher numbers, and in eastern and central Ohio where higher populations of the brown marmorated stink bug were found in homes last fall. If brown marmorated stink bugs or high populations of the green stink bug are found on soybeans, we would like to hear about it (hammond.5@osu.edu). We have recently developed tables of the insecticides registered on both corn and soybean that are labeled for control of stink bugs and placed them into Bulletin 545 that is available at our Agronomic Crops Insects web site, http://entomology.osu.edu/ag/.

Where to go to find Agricultural Chemical Use Statistics

From time to time I want to find out the latest statistics on Agricultural Chemicals and Pesticides use in the U.S. You may have had the same need one time or another. So, where do you go for the most accurate data? It is The U.S. Agriculture Department's National Agricultural Statistics Service (NASS).  The data given on this site may not be as current as last year, but they are the most current and reliable data we can find right now. But sometimes, surprisingly, they are pretty current. For example, they just published the 2010 Agricultural Chemical Use survey data for vegetables. The data includes statistics for on-farm use of commercial fertilizers, agricultural chemicals and integrated pest management practices from producers of targeted vegetable crops. The agricultural chemical use estimates focus on the acreage treated with herbicides, insecticides, fungicides, and other pesticides.

Here is the URL that will take you to their site:
http://www.nass.usda.gov/Surveys/Guide_to_NASS_Surveys/Chemical_Use/
A specific link on the URL above takes you to another "page" where you can find use data for specific chemicals and crops for a given year: Here is the direct URL for that site:
http://www.pestmanagement.info/nass/app_statcs1_year.cfm

For example, if you want to know Pounds of 2,4, D (Active Ingredient-- A.I.) per year in Ohio in Corn, you get a chart shown below. You can also get statistics for:
-- % average treated acres
-- Number of applications
-- A.I. per application (lb/ac)
-- A.I. per year (lb/ac)

 

OSU Extension providing pesticide recertification credits at GVM Field Day.

Ohio State University Extension will have a strong presence at a Field Day hosted by GVM West in Bellevue, Ohio on Thursday, September 8, 2011. Although GVM sponsors the event chiefly to promote their products, the company graciously supplies OSU Extension with a separate tent to accommodate pesticide training that is open to the public.

From 10:45 to 11:45 a.m. Extension Educators will lead discussions on managing glyphosate resistant weeds and the economics of protecting the 2011 crop through harvest. This session will count for pesticide recertification credits (2A and 2C commercial or category 1 private).

At 1:00 p.m. Extension Educators Dr. Steve Prochaska of Crawford County and Mike Gastier of Huron County will offer one hour of Core training for both commercial and private applicators. Certified Crop Advisor credits will be available for both sessions in the categories of Crop Management and Pest Management.

GVM West is located at 4341 Sandhill Road in Bellevue, Ohio. Their facility is adjacent to US Rt 20 between Bellevue and Monroeville. The actual site of the Field Day is just south of Rt 20 on Sandhill Road. The event begins at 9:00 a.m. and concludes at 4:00 p.m. This is a great opportunity to stay up to date on the latest fertilizer and pesticide application technology and also get recertification credits.

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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.