USWBSI Blog

Paul Murphy and I had a good visit to Fargo last week where we were graciously hosted by Marcia McMullen, Xiwen Cai, Elias Elias, Mohammed Mergoum and Tom Anderson.  Not much scab due to the hot dry weather but we learned a lot.  For example, I was very impressed with the misted scab nursery which included about 15,000 hill plots (durums + springs) that had been planted with a headrow planter set on the shortest row length.  Very efficient.  This is the type of info that should go under tips and tricks.  Also impressive is the number of extension publications on scab that NDSU has generated.  We need to make sure that everyone is aware of these sorts of publications, so let the NFO know about them.  One of the high points of the trip was riding with Tom Anderson in his combine as he harvested a field of Oklee wheat.  Also impressive was the wide hybridization work going on in Dr. Cai’s lab and greenhouse.  We need to figure out ways of doing these kind of visits en masse (maybe in lieu of the Forum some year?).  If you have any ideas along these lines, please post them on this blog site.

Data received from cooperators for the 2006 Uniform Southern Winter Wheat Scab Nursery are being summarized and posted on the SUNGRAINS web site at

http://www.agronomy.lsu.edu/sungrains/sungrains.html

Click on ‘Data Files’ and then ’USFHBN running means’

This should help in making decisions for fall greenhouse and field plantings.

I was recently told that moisture trumps tempterature as far as FHB goes, and it seems to be the case here.  After a long delay of no scab symptoms due to prolonged cool weather, we have them in abundance in the irrigated grain spawn nursery, where we sprayed conidia with no irrigation, and in general throughout our breeding nurseries here.  I don’t know how this relates to the KY crop as a whole; harvest should begin this coming week and we should be hearing some reports on DON levels by week’s end.  One of the interesting things about the scab in the non inoculated breeding plots is that we had to moldboard plow last fall, since it was too dry to chisel plow.  thus, we had minimal corn residue, but lots of scab anyway.

One of the problems that our scab screening effort has is that we often are hotter and drier than many parts of the main scab affected area.  We have used our misting system to cool and add the needed moisture to our plots.  In talking with our colleagues, many have gone to a “fogging” mist type of system.  In NE where the wind blows most of the day and night, a fog will not settle in the screening plots.  Does anyone have an idea of how droplet size affect the screening nurseries.  We use a small droplet, but can not use the “fog” type.

Also, we have routinely selected the best lines from our FHB populations and are beginning to see some advanced lines with known FHB tolerant QTLs.  However, the frequency of FHB tolerant lines is lower than I would like–presumably due to the relatively raw germplasm we initially used.  With the advent of our advanced lines; Glenn (HRS) and other HRS lines; and the elite soft winter wheat lines frm the eastern U.S., I believe I can fix the 3BS and 5AS QTL in future populations just by careful parent selection. While still working with highly segregating populations, I am thinking of harvesting the best phenotypic types, and having them screened for 3BS and 5AS markers.  For the “unselected” lines, I am thinking of snapping a single head per plant with the idea that if the phenotypically best lines do not have the markers (or they are in low frequency), I can sample the remaining population to capture the genes I want and they at least will be in a better background than the raw starting material.  Any thoughts? 

As in much of the Great Plains (e.g. disasterous drought in Texas, Oklahoma, and parts of KS and NE), we are hot and dry coming into flowering.  It is beginning to cool off now, but we willhave to see if moisture will come with the coolness. 

It has been suggested that the scab initiative has bred for “DON tolerance rather than DON protection”.  Any thoughts?

Reports from cooperators in AR, KS, and KY all indicate that wheat has flowered and is advancing through the early to mid-dough stages of development. It appears that head scab has not been a significant problem in KS or AR this year largely because for dry conditions that prevailed during critical periods around flowering that influence reproduction of the pathogen and disease development.Kentucky

Don Hershman, University of Kentucky, reports that wheat in KY flowered during the last week of April and early May. Weather prior to this period was dry and had above normal temperatures; however, things changed dramatically during the flowering period. Don indicated that frequent rains and cool temperatures (daily max between 50-65 F) during most of the flowering and grain-filling growth stages. Despite the frequent rains, the disease forecasting models developed by the cooperative epidemiology effort indicate that the risk of major epidemic was low during most of this time period. To date Don and his colleagues from KY indicate that the levels of head scab are low, and suggest we should know more by early next week. It appears that the dry conditions in April and cool temperatures associated with the frequent rain may have limited disease development.

Indiana

Indiana was also impacted by the frequent rains during early May. Greg Shaner indicates that wheat in Southern IN was flowering during this time and we had several communications about the risk of scab in this area. At this time we feel that temperatures have been too cool for fungal reproduction and disease development. Northern IN and parts of OH are now heading in many areas. I feel it is wise to watch these areas over the next few days. If rain persists and temperatures increase we may see an increased risk of scab in these states.

The word across the state is that scab symptoms are minimal to date.  Very cool weather may have played a role, because there was plenty of rain during flowering.  At our Princeton nursery where we put down scabby corn and sprayed conidia but did not irrigate, there were just a few hits in early lines.  Obviously there is still concern about DON, since we have had years with late infection and apparently sound kernels that had high DON.  Barley harvest will probably begin late next week, if the sun ever shines again!

The rain continues, but cool temps are leading everyone to expect low Fusarium head blight levels.  Maybe symptom expression will just be delayed?  In any case, the crop has slowed down and the yield level looks excellent if it all doesn’t fall over.  Plenty of mildew and septoria, little if any leaf and stripe rust.

More rain, lots of very early lodging.  Still cool, but I wouldn’t be surprised to see a fair amt. of Fusarium head blight develop.  At the moment in this part of the state, there is a raging mildew epidemic.