By Pat Porter, Texas AgriLife Extension
While it is still too early to know how the 2016 sugarcane aphid season will go, early indications are that it might be more substantial in southern Texas than last year, and the aphids might move north more quickly than they did in 2015.
Robert Bowling, Extension entomologist in Corpus Christi, said on February 24th, "SCA populations are on the increase and, if current environmental conditions persist, south Texas may see the first aphid flights very soon." He reported that he and others were finding plants with 2,000 - 3,000 aphids per leaf in isolated places or small patches.
South of the Metroplex, aphids are being found five to six weeks earlier than last year. Xandra Morris, IPM Agent in Hill County, reported finding sugarcane aphids in her February 18th blog post. The first finds last year were around April 1st. We think the prolonged and heavy rainfall last year caused a lot of mortality to sugarcane aphids, and it is an open question as to whether rainfall will slow the spread this year.
On the High Plains we are going to open our overwintering cages in the next week or so and see if there was any aphid survival. We have 9 locations from San Angelo to north of Amarillo, and results will be reported on this website.
On balance, it looks like sugarcane aphids are going to move northward earlier this year than last year unless we get the El Nino rainfall that the weather forecasters keep talking about as a possibility. For High Plains sorghum we are strongly recommending a neonicotinoid seed treatment for all sorghum, even dryland.
These seed treatments will buy about 45 days of protection at a cost of around $2 per acre. We are also recommending that sorghum be planted as early as possible so that is as far along in development as possible when the aphids arrive. The logic can be seen in the following table from Mississippi State University for possible yield loss when plants reach threshold at specific crop growth stages.
It is important to note that the treatment thresholds for South and Central Texas are very different from those on the High Plains. On the High Plains we need to treat aphids significantly sooner than downstate (our thresholds are lower), and a forthcoming article will explain the thresholds in more detail.
We will continue to monitor the situation statewide and post the news here.