Friday, March 27, 2015

Excellent Mississippi Pre-season Publication

Angus Catchot and the other entomologists at Mississippi State University have written an excellent pre-season guide for dealing with sugarcane aphid this season, and they have incorporated most of the "lessons learned" in 2014. The publication is here: http://www.mississippi-crops.com/2015/02/24/management-guidelines-for-sugarcane-aphids-in-ms-grain-sorghum-2015/ .

There are two places where the Mississippi suggestions differ from what might be applicable in Texas. The first is that Mississippi suggests that, based on anecdotal information (but not research), narrower rows and/or higher plant populations may result in lower sugarcane aphid populations. The closest information we have on this topic is that Roy Parker demonstrated fewer greenbugs on narrow row sorghum on the Gulf Coast in the early 2000s. Whether or not narrow rows and/or higher plant populations affect sugarcane aphid, we do know that in many parts of Texas with limited rainfall or irrigation capacity it is not wise to increase plant populations beyond the available water.

Secondly, the Mississippi entomologists use a threshold based on percentage of plants infested and established aphid colonies present. This method allows for rapid scouting and we have no doubt that the action thresholds based on this method are valid in Mississippi. However, the Texas threshold is based on aphid counts or estimation of the numbers of aphids in colonies. We have not investigated the Mississippi method in Texas production.  Additionally, the Mississippi article provides different thresholds depending on growth stage and warns that pre-boot infestations can result in 81 - 100% yield loss, and projected yield loss ranges are provided for later growth stages.