Lebanon Crop Management Video

Loading...

09 May 2016

Head Scab Condition ripe for infection in the Lebanon Area

Here we go with conditions favorable for infection at the time wheat is pollinating.. The key is the weather  The most favorable conditions for infection are prolonged periods (48 to 72 hours) of high humidity and warm temperatures (75 to 85 degrees Fahrenheit). However, infection does occur at cooler temperatures when high humidity persists for longer than 72 hours. Early infections may produce air-borne spores, which are responsible for  secondary spread of the disease, especially if the crop  has uneven flowering due to late tillers.  This is the web address for the current forecast month.  http://www.wheatscab.psu.edu/riskTool_2012.html This is a  guide not to replace the conditions observed as above. Right now about the whole state is red indicating the best conditions for infection. Keep this in mind with Barley as well as some heads have emerged last week.
 Early Maturing Wheat in the Lebanon area  is beginning to flower and conditions are favorable for infection. I talked to a local grower. From his spray records last year he sprayed May 25th when flowers were out this year might be somewhat different.  Prosaro and Caramba, only provide about 50-60% suppression when applied at flowering. Depending on the weather conditions, and the baseline level of disease and toxin, 50-60% suppression may be sufficient to avoid or reduce price discounts and dockage. For instance, 50-60% suppression would bring vomitoxin levels from 4-6 ppm to 2-3 ppm, or under more favorable weather conditions, from 8-10 ppm to 3-5 ppm. So, this is what you can expect, suppression, not 100% control. Efficacy is greatly reduced when applications are made before or after flowering, so expect little or no vomitoxin suppression from application made for foliar disease control between flag leaf emergence and heading.
Flowering is when anthers (the yellowish male part of the flower) are seen sticking out of the heads(see picture below). This typically occurs 3 to 5 days after heading. Anthers first emerge in the central portion of the head – this is called early anthesis or early flowering and is the growth stage at which fungicides should be applied for best results against scab and vomitoxin. If conditions are warm, it takes less time between heading and flowering, however, under cooler conditions, it may take longer, up to 5 or more days after heading, and flowering may last for several days. Main tillers (main stems) usually flower first, followed by secondary tillers (side stems). So, the flowering pattern may vary from field to field, depending on the variety and local weather conditions. This variation affects the risk for scab and vomitoxin and fungicide efficacy against the disease and toxin. In general, a well-timed application to a field with a narrow flower window will likely provide better scab and vomitoxin suppression than a poorly timed application or an application made to a field that flowers over several days.
Prosaro and Caramba are the two choices for application at this time. 
Prosaro 421 SC 6.5–8.5 ounce/acre  30 days HI
prothioconazole + tebuconazole
Caramba 10.0–17.0 ounce/acre  30 days HI
metconazole








 Applications with twin jet nozzles and or increased  gallonage (20gpa) is critical to coat the heads with the material.  The point here is the target is a vertical head so the product needs to be applied at an angle to the head to coat all the spikelets.  Angling the nozzles and treating two different directions is also an option. 

1 comment:

  1. In a discussion this morning commercial applicators are prioritizing fields that were planted into corn stubble first then in wheat planted into soybeans. Sounds like a great method to ensure success.

    ReplyDelete