This is going to be another year where spraying a fungicide on intermediate to susceptible varieties to stripe rust is going to make a big yield difference.  Fields and test plots that were not treated in Southern Kansas and Central Oklahoma have high severity of stripe rust on the flag leaves.  The cool, moist weather this week is excellent for grain filling but is also highly conducive for continued development of stripe rust.  With this in mind, I urge producers in areas where the wheat hasn’t yet bloomed to consider a fungicide application if they haven’t already pulled the trigger.   Just keep in mind what is on label for some of these fungicides as we get later in wheat development.

Everest is one of the more susceptible varieties to stripe rust in the plots across South Central Kansas but stripe rust is a disease that we can manage.  Its fusarium head blight, barley yellow dwarf, and leaf rust resistance disease package and acid soil tolerance still makes it one of the stronger varieties for the Central part of Kansas and Oklahoma.  Farmers that grow Everest must budget in a fungicide with our total loss of protection to the 2012 stripe rust race change.  Zenda, the Everest replacement, is looking very promising as it has been one of the cleaner varieties in regards to stripe rust in the few test plots I’ve seen it at.  Allan Fritz keeps mentioning that Zenda finishes extremely well and looks forward to seeing how it does this year across more locations.

Leaf rust can be found in low levels in Central Kansas.  The weather forecast next week will be more conducive for leaf rust development and it could be a race to the end on susceptible varieties.

Fusarium head blight can be found in very low levels across South Central and Southeast Kansas.  The bigger concern for head scab is going to be in the Northern part of Kansas.  Conditions have been more favorable here during flowering for disease development.  Fungicides such as Prosaro and Caramba applied at flowering can provide some control but ultimately work best when in combination with a variety such as Everest that has the best scab resistance.

Wheat streak mosaic virus (WSMV) is more of an issue in South Central Kansas this year as it has been reported as far east as Cowley County.  There is not much we can do in the field to combat WSMV outside of planting a resistant variety.  Oakley CL and Joe both contain the WSM-2 gene giving them some of the best resistance on the market, but they aren’t all that well adapted to the central corridor of Kansas.  The demo plots in Ness County illustrate the usefulness of this WSM-2 gene in Oakley CL, but keep in mind that this gene does not give these varieties resistance to some of the other viruses that are very similar to WSMV like High Plains Virus and triticum mosaic virus.  K-State has a few advanced lines with intermediate levels of resistance to WSMV that may be suitable options in the future for South Central Kansas and North Central Oklahoma.  Ultimately we need to be vigilant in controlling volunteer wheat this fall at least two weeks before planting to minimize the green bridge.

Aphid feeding has led to noticeable levels of barley yellow dwarf (BYD) across the state and is fairly common in test plots and on the Wheat Quality Tour.  However, outside of a few fields here and there that are showing severe levels, levels of BYD are normal.

Finally, Larry, Joe, and Tatanka have looked very promising at all the locations I have seen them at.  Larry has been one of the cleanest varieties across the board outside of picking up a little leaf rust late at the Ellsworth variety performance trial.  Joe is right in line with Larry in how clean it looks and will be interesting to see if sprouting becomes a concern in some of the more Eastern test plots it is in.  Tatanka has also been fairly clean but does have some lodging concerns in the intensive management study at Ellsworth.  We are also seeing lodging issues in other varieties such as Monument at this same location though.

 

Figure 1 Everest with no fungicide applied under heavy stripe rust pressure in a Lahoma, Oklahoma test plot.

Figure 1 Everest with no fungicide applied under heavy stripe rust pressure in a Lahoma, Oklahoma test plot.

 

Figure 2 Heavy barley yellow dwarf infestation in Sumner Co., Kansas.

Figure 2 Heavy barley yellow dwarf infestation in Sumner Co., Kansas.

 

Figure 3 Larry under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

Figure 3 Larry under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

 

Figure 4 Zenda under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

Figure 4 Zenda under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

 

Figure 5 KanMark under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

Figure 5 KanMark under intensive management (left – two fungicide passes + extra N) and standard management (right – no fungicide and extra N) at the Ellsworth, Kansas variety performance trial.

By Bryson Haverkamp