Posts Tagged ‘rice stink bugs’

Field Notes, August 31, 2010; heat effects, verification yields, stink bugs

September 16, 2010

The past three weeks I have had several calls with the same basic theme; “Why are my yields falling off?”  The simple answer is heat.  It has been much too hot especially at night for successful pollination and grain fill.  This has also led to more Bacterial Panicle Blight than we have seen in several years.  Even second crop is being affected because temperatures have remained high throughout most of this month and a lot of second crop rice is or has already flowered.

I have also had questions about pecky rice.  Normally we associate pecky rice with rice stink bug damage and secondary damage from fungi that enter through the wound made by the stink bug.  This year there have been instances where there did not appear to be heavy stink bug populations, but pecky rice was reported.  There is no simple explanation for this.  Again I suspect excessive temperatures and disease are playing a role.

Other callers have asked about late season stink bug control. My philosophy on stink bugs is to make a final sample at the time of drain recommendation.  If I encounter a hatch out or have been sitting on a 2/3 threshold for a couple of weeks, I will recommend a spray because it will be two to three weeks (if everything goes right) before harvest and during that time the numbers are only going to go up.  Not everyone agrees with this practice. I hate stink bugs. We did exactly that in one verification field that had already been sprayed once and I’m glad we did because rain delayed harvest so that there were 4 weeks between drain and harvest.  Stink bugs were still present at harvest. I hate to think of what the numbers would have been if we had not sprayed. It was also a seed rice field which helped to justify the additional spray.

Below is a table summarizing yields from the Rice Research Verification Program this year. It was a much smaller program with only three fields involved; however it was as challenging a year as any.  In spite of the problems I was surprised at how little difference in yields we experienced between this year and last year.  I suspect if we had 9 fields this year the differences would have been greater.

Parish Acres Variety Cwt/A green Bbl/A green Bu/A green Cwt/A dry Bbl/A dry Bu/A dry
Avoyelles 41.8 Cocodrie 85.63 52.9 190.3 80.57 49.7 179.0
Jeff Davis 35.8 CLXL745 91.04 56.2 202.3 87.38 53.9 194.2
St. Landry 31.3 CL111 73.46 45.3 163.2 71.71 44.3 159.4
Average     83.91 51.8 186.5 80.26 49.5 178.4
                 
2009     86.06 53.1 191.3 81.31 50.2 180.7
2010-2009     2.15 1.3 4.8 1.05 0.7 2.3

Rice Stink Bugs, Narrow Brown Leaf Spot, Cercospora, Panicle Blight

June 23, 2010

Yesterday we found lots of rice stink bugs in one of our verification fields.  Other folks out checking headed rice said they are finding them too.  If rice is headed they should be checked for stink bugs by sweeping with an insect sweep net.  We had more than one insect per sweep which is more than 3 times the threshold value.

We also found Narrow Brown Leaf Spot which is caused by Cercospora janseana.  At least two varieties were involed, CL161 and CL151.  Because of the confusion with Brown Spot the disease has been commonly called Cercospora to differentiate the two.  It requires propiconazole containing fungicides to control it.

In this heat we are also setting up for an outbreak of Bacterial Panicle Blight which will not be evident until grain development begins.