Research is looking at history to find out what grove characteristics are favorable to Asian citrus psyllids and possibly adjusting urban psyllid control efforts in the state when a certain infestation level is reached.
Cooperative Extension Farm Advisor Brad Daugherty is doing research on the history of Asian citrus psyllids in California. With the pest rampant in Southern California, Daugherty started looking at factors that make a grove more susceptible to infestation. “If you looked at the patterns for which groves it first arrived at, there’s aspects of the grove themselves — basically the bigger groves with more edge. That made them bigger targets,” Daugherty said. “But also, the isolated groves out by themselves with nothing around were invaded at a slightly slower rate. So being connected to major urban areas where the psyllid was already present is a really strong predictor.”
Daugherty said there’s a point of infestation where that changes. “What we are starting to see in around 2012 and 2013 when more groves were infested, it’s proximity to other groves was a major factor,” Daugherty said. “When you got an area with lots and lots of acreage of citrus, once one of them gets invaded, it seems to kick in this cascade where all the other groves around it get infested.”
That change means California might need to adjust its urban efforts against the pest. “Those patterns would suggest that here in Southern California, by now most acreage is infested to one degree or another, so it’s kind of a moot point, but the extent of which controlling stuff in urban areas now I question. However in the Central Valley where it isn’t quite as widespread, containment in the urban areas is critical,” Daugherty said. “We need to maintain those control programs in urban areas in the Central Valley and devote as many resources as we possibly can and that may mean moving some of the resources in Southern California up there.”
“It’s probably a front that we have a little more control over,” Daugherty added.