Lukasz Stelinski, Freddy Ibanez, Phil Stansly, and Gene Albrigo. University of Florida, CREC

Transcription

1 Addressing whether there is a need for continued vector management under HLB stress Lukasz Stelinski, Freddy Ibanez, Phil Stansly, and Gene Albrigo University of Florida, CREC

2 Do insecticides sprays affect yield in trees that are already infected with HLB? Objective: Evaluate effect of insecticides and foliar nutrition on ACP, HLB incidence, and yield 13 acres Valencia on Swingle Planted June 2001 Defoliated 2005 and 2006 for canker control HLB detected spring x 2 factorial (RCBD 4 reps) 16 plots Average 108 trees per plot Treatments began Feb 2008 No- Insecticide Insecticide No-Nutritional Control Insecticide Stansly, P.A., Arevalo, H.A., Qureshi, J.A., Jones, M.M., Hendricks, K., Roberts, P.D. and Roka, F.M., Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing. Pest management science, 70(3), pp Tansey, J.A., Vanaclocha, P., Monzo, C., Jones, M. and Stansly, P.A., Costs and benefits of insecticide and foliar nutrient applications to huanglongbing-infected citrus trees. Pest management science, 73(5), pp Nutritional Nutritional Nutritional + Insecticide Phil Stansly

3 Cumulative of ACP adults per tap Insecticide Nutrition Insecticide + Nutrition Untrea te d Cumulative adult ACP per tap sample Mar- 08 Jun-08 Aug-08 No v-08 Feb-09 Apr -09 Jul-09 Oct-09 Dec -09 Mar- 10 Jun-10 Aug-10 No v-10 Jan-11 Apr -11 Jul-11 Sep-11 Dec -11 Mar- 12 May-12 Aug-12 Two taps/tree : 10 randomly selected trees in the middle bed of each plot : 6 randomly selected trees per two randomly selected stops per plot Sprays (Avg 5/year) dormant + threshold based on 0.5,0.2 and finally 0.1 ACP/TAP Oct-12 Jan-13 Apr -13 Jun-13 Sep-13 Dec -13 Feb-14 May-14 Jul-14 Oct-14 Jan-15 Phil Stansly

4 Boxes per Acre b b b Untrea ted Nutrition Insecticide Insecticide + nutrition a a a ab ab a b b c c ab b a b a a ab b b a a b ab a a Phil Stansly

5 Incidence of HLB: Assessed by PCR on 20% of trees per treatment 100% Control Insect Nutr Nutri+I nsect % of HLB positive plants 90% 80% 70% 60% 50% 40% 30% 20% 10% Rose from 30% to > 90% in 18 months Highest initially in Nutrient Only plots If treatments will help, it will be by reducing intensity of HLB 0% Oct- 08 Feb-09 May-09 Aug-09 No v-09 Mar- 10 Jun-10 Sep-10 Jan-11 Phil Stansly

6 Project Title: Addressing whether there is a need for continued vector management under HLB stress USDA, APHIS Multi-Agency Coordinating Group (MAC) PIs: L. Stelinski (UF) and M. Setamou (Texas A&M) Project initiated in January 2018; Initial funding duration 2 yrs.

7 Laboratory experiments Evaluate the effect of varying CLas inoculation frequencies on HLB progression and plant defense response Specific measurements 1. CLas titer within various plant tissues (mature leaves, flush feathers and roots) 1. Salicylic acid-induced plant defense response 2. Disease progression

8 Hypotheses H 1 : Suppression of ACP populations in citrus groves with improved vector management will reduce CLas titer in citrus trees via decreased superinfection H 2 : Decreasing super-infection will decelerate decline CLas-Infected CLas-super-infected Accelerated decline ACP populations Improved vector suppression

9 Experimental design (laboratory microcosm) Ø One-time inoculation: Testing the all it takes is a single infection hypothesis. Do we need zero-tolerance? CLas-infected ACP Uninfected ACP (Negative control) Plants are exposed to adult ACP (CLas infected vs. uninfected) allowing 7 d inoculation period.

10 Experimental design (laboratory microcosm) Ø Regularly pulsed inoculations (Simulating ACP control followed by invading immigrants) CLas-infected ACP uninfected ACP Plants are exposed to adult ACP (Clas-infected vs. uninfected) every 30 days (monthly) for an inoculation period of 7 days. This process is continuously repeated.

11 Experimental design (laboratory microcosm) Ø Continuous inoculation (Simulating constantly reproducing resident population of ACP) CLas-infected ACP uninfected ACP Plants are exposed to all life stages of ACP (CLas infected vs uninfected infected) continuously during the entire experiment.

12 One-time inoculation: Pulsed inoculation: Continuous inoculation: Hot ACP Uninfected (control) ACP

13 Preliminary results from laboratory microcosms Summary of CLas titer, plant phenotype and gene expression results: -No symptoms or CLas infection among negative control plants exposed to uninfected ACP or not exposed to ACP at all. Treatments Percentage of CLasinfected plants (3 months after inoculation) HLB symptoms Genes involved in SApathogen response and metabolism One-time inoculation 33% + up-regulated Multiple inoculations 0% ++ up-regulated Extended inoculations 0% +++ up-regulated Abbreviations: (+) normal leaves, (++) mature leaves with yellowing, (+++) mature and young leaves are deformed, stunted in growth with yellowing. -SA response upregulated by ACP feeding irrespective of whether they were carriers of CLas.

14 Field experiment: Regular interval sprays versus sprays timed to tree (ACP lifecycle) phenology Control consists of calendar sprays: Intervals between sprays are determined by length of treatment efficacy and dormant sprays and the first spray thereafter often timed to first flush. Treatment is the Dr. Gene Albrigo method: Spray for adults at bud break at the beginning of each new flush before there is feather flush on which the adults can lay eggs. With a second spray as ACP begins to reappear > 60 days of low ACP populations seem possible.

15 Experimental design for Field expeirment Danitol (pyrethroid) Movento (spirotetramat) Mineral oil (435 Oil 98.8) Minecto Pro (abamectin + Cyantraniliprole) Mineral oil (435 Oil 98.8) Pesticide application Mineral oil (435 Oil 98.8) Pesticide application Jan Feb Mar Apr May Jun Jul Aug Dec Locations Mature leaves (N=4-5) collected per tree (N=5) Ø Total number of ACP (taps) Ø Titer of CLas (DNA extractions) 1. Fort Meade L1 2. Fort Meade L2 3. Fort Meade L3 4. Frostproof L4 5. Frostproof L5 6. Frostproof L6

16 Initial results-acp counts ACP Counts (Adults, nymphs, eggs) Treatment sprays 1 st Control adults 2n d 1st Treated adults FB Control nymphs 2nd 3 rd Control - eggs 3rd Grower std sprays Treated nymphs Treatment: 1/16 Danitol, 2/12 Movento + oil, 4/12 Movento + Malathion

17 Initial results-acp counts ACP Counts (Adults, nymphs, eggs) Grower std sprays 1st 1 st 2 nd Treatment block sprays Control adults FB Treated adults 2nd 3 rd Control nymphs 3rd Treated nymphs 1/16 Danitol, 2/12 Movento + oil, 4/12 Movento + Malathion

18 Initial CLas titers measured to date

19 Conclusions Vector management with Gene Albrigo method of timing sprays with bud break reduced ACP more effectively than non-targeted calendar sprays. We expect to observe a reduction in CLas titer associated with a suppression of ACP populations during the previous season s feather flush. Whether reducing super-infection will cause decreased CLas titer associated with improved health is to be determined. Are insecticides worth it? Ø The preponderance of available data supports this hypothesis Ø Has this new MAC-funded investigation produced unequivocal supporting data? Not yet; work is in progress

20 Acknowledgments CRDF funded previous work P. Stansly Stansly, P.A., Arevalo, H.A., Qureshi, J.A., Jones, M.M., Hendricks, K., Roberts, P.D. and Roka, F.M., Vector control and foliar nutrition to maintain economic sustainability of bearing citrus in Florida groves affected by huanglongbing. Pest management science, 70(3), pp Tansey, J.A., Vanaclocha, P., Monzo, C., Jones, M. and Stansly, P.A., Costs and benefits of insecticide and foliar nutrient applications to huanglongbing-infected citrus trees. Pest management science, 73(5), pp USDA-APHIS-MAC; Grant # AP17PPQS&T00C163 is funding this continuing project L. Stelinski and M. Setamou