Connie’s Comments by Connie Strunk, Turner County Extension Educator—Agronomy 

June 7, 2009

  

            Who would have thought that June would be so cold and dry?  The rain that we received the last few days has been a blessing for many landowners.  Now if we could only do something about these cool temperatures! 

Actually, my husband and I have welcomed the rain and cool temperatures that we have had lately.  The reason?  All of those hedges that I have mentioned before sustained winter dieback an d in order to save them we had to cut them down to 3 inches to hopefully rejuvenate them.  Keep in mind that I had cut down six hedges as a test pilot to prove to my husband that this was what we needed to do to the others.  Dave said that if these “test pilot” hedges worked out than he would consider doing it to the rest of them next year.  In order to save the hedges, Dave reluctantly cut down all the other hedges with me.  Now our yard is very open and exposed.  I am hoping that the next hedge report that I give will only contain good news.   

Since most of the wheat is near heading or has headed out, wheat farmers need to think about Fusarium head blight (head scab or scab) control.        

            Scab is a concern for winter wheat and small grain farmers when the temperatures during the day are between 70-85°F, night time temperatures are between 65-80°F, and when we have moisture (dew or rain) available.  We have been a little cool lately so the fungus takes a little longer to get established and sporulate but it can still get started with prolonged moisture. 

The reason this disease is so hard to control is that there is only a small window of opportunity for scab control and that time is at flowering.  If you apply your fungicide before flowering you will protect your flag leaf from diseases but you will not receive any protection for scab.  The same goes for applying the product after flowering (not preventing scab) plus you will also be using the product off label when it comes to scab control.

Fusarium spp. fungi are the causal agents in scab.  These fungi over-winter on crop residue such as cornstalks, wheat stubble, and grass residue.  Corn, in particular, is readily colonized by these fungi.  These fungi actually help break down the stalks.  We have seen scab be quite severe when wheat follows corn in a rotation.

            The scab spores produced on the residue are blown by the wind to the wheat heads where germination and infection of the seed head takes place during warm, moist weather.  Infections are most numerous and serious during flowering.

            Heading occurs when the last internode, which supports the head, pushes the head out of the flag leaf collar.  Generally, flowering in wheat begins three to four days after the head emerges.  Flowering begins from about the middle section of the main stem head and progresses to the top and bottom of the head.  Flowering is complete within a few days.

             Timing of application is everything when it comes to the control of scab.  To be most effective in controlling scab, fungicides must be applied at the beginning of flowering.  This means that once the wheat starts heading, you have three to four days to get a fungicide applied so it is on at flowering.

            Each producer will have to make their own decision whether to treat or not to treat for scab control.  A big part of that decision will depend on what the weather is like at the time of heading and whether your variety is resistant or susceptible to scab.  Remember, that wet and humid weather conditions are favorable for wheat to be infected with scab.

            For more information please feel free to contact me at the Turner County Extension Office at (605) 297-3112.