Because the Asian citrus psyllid stakes its reproduction on new citrus flush, there is a lot of interest in tailoring management to citrus phenology. “Phenology” is an uncommon word, but it boils down to how plant development changes over time. For instance the development of the spring flowering flush is a phenological process and names like “feather flush,” “popcorn,” and “full bloom” describe phenological stages.
Gene Albrigo has been involved in phenological modeling to predict flowering intensity and bloom time since well before the HLB era. He has recently turned to using this model to help improve psyllid management in two ways: reducing psyllid reproduction on new flush through pre-emptive psyllid management, and reducing negative impacts of insecticides on bee pollinations. In other words his goal is to kill adult psyllids before they can lay eggs on tender new flush but not hurt pollinator bees with applications late in the flush, when flowers have emerged. This can be done by using the models he and collaborators developed and have maintained for more than 10 years.
Gene has worked with several regional growers, selecting some blocks to manage psyllids based on phenological predictions, leaving others as controls with calendar or sampling-based sprays.
Gene recently reported results from the first two years of developing this approach. Results are positive, with reductions in adult psyllid numbers and egg-laying using the phenology-based approach, spraying once just prior to budbreak and again about 4 weeks later. This also allowed a bloom period that was free of insecticide applications, leaving the pollinators to range at the appropriate time. These results are promising for psyllid management during the floral flush, and I expect this approach to expand to become a standard practice.
Kaolin particle films are having promising effects in managing Asian citrus psyllid, but they also have effects on photosynthesis. To help dig into this, a new member has joined our lab: Juanpablo Salvatierra Miranda, or “JP.” He’s 4 months into his first round of experiments, and he’s already made some important observations. He’s focusing on the how photosynthesis changes over the course of a day – “diurnal photosynthetic dynamics” – in response to kaolin particle films of different colors.
JP comes most recently from his native Chile, where he was working for a private agricultural research company. He has experience in horticulture of vegetables, wine grape, and citrus. His Master’s thesis will consider how different colored films affect growth and photosynthesis, as well as how these affect the development of huanglongbing symptoms in the field.
Kaolin films are showing promising results in management of Asian citrus psyllid. I recently presented preliminary results from our trial of Surround kaolin clay product and a Surround that we have modified with a red dye in presentations to the Polk County OJ Break and to the Citrus Research and Development Foundation research lunch. To see the complete presentation click here.
The results are promising: Over the course of the first year after planting we saw an 78% reduction in mean psyllid numbers per tree in the white kaolin treatment. Thus far, this has also translated in lower infection rates, with a mean of 10% infection in the white kaolin versus 25% in the foliar insecticide treatment. These results are early, so we should be cautious about jumping to conclusions. However, other studies have produced similar results, and this means that growers should consider kaolin as a viable practice to incorporate into their management programs.
Myrtho Pierre is the new biological scientist in the lab. She is already taking charge of many of our specialized measurements. Myrtho worked for years in horticultural production and consulting in Haiti, and she has been working “behind the scenes” here at CREC for 4 years (3.5 years longer than I have!). She brings organization and friendliness to the lab, and she is already knee deep in greenhouse management and calibration of chlorophyll fluorescence and root respiration measurement. I look forward to good things to come.