A 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Phosphorous Acid (ppm) PH Spring PH Fall+Spring PH Fall PH Spring+Spring PH sprays Water injected control B 0.00 0.02 0.04 0.06 0.08 Cyprodinil (ppm) DC Fall+Spring DC Fall DC Spring+Spring DC Spring C 0.000 0.004 0.008 0.012 0.016 0.020 0.024 Difenoconazole (ppm) DC Fall+Spring DC Fall 7 DC Spring + Spring DC Spring D 0.0 0.1 0.2 31-May-2013 18-Jun-2013 10-Jul-2013 30-Aug-2013 Active ingredient (ppm) DC sprays - difenoconazole DC sprays - cyprodinil E 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 Phosphorous acid (ppm) PH Fall PH Fall+Spring PH Spring PH Spring+Spring PH Sprays Water injected control 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 Cyprodinil (ppm) DC Fall DC Fall+Spring DC Spring DC Spring+Spring F 0.00 0.02 0.04 0.06 Difenoconazole (ppm) DC Fall+Spring DC Fall DC Spring DC Spring+Spring 0.0 1.0 2.0 3.0 4.0 25-Oct-2012 21-Apr-2013 1-May-2013 15-May-2013 29-May-2013 12-Jun-2013 26-Jun-2013 10-Jul-2013 Active ingredient (ppm) DC sprays - difenoconazole DC sprays - cyprodinil Figure 1. (A) Trunk- injected compounds are precisely delivered, translocated via xylem, and distributed in the tree canopy. (B) Topical pesticide delivery leads to off-target pesticide solution losses of up to 44-71%, which negatively affect the environment. A B 3. 1. RESULTS - APPLE SCAB CONTROL 1. INTRODUCTION • We evaluated trunk injection as a precise method for delivery of compounds for control of apple scab and fire blight diseases (Aćimović et al. 2013, 2015). • Tree injection severely reduces pesticide drift, applicator exposure, and impact on non- target organisms in the environment (Fig. 1). This method could increase the sustainability of tree fruit production. • Season-long control of apple scab (Venturia inaequalis) could be achieved by differentially timed trunk injections of fungicides and plant resistance inducers such as potassium phosphites (Aćimović et al. 2015). 2. MATERIALS AND METHODS Table 1. Application schedule for trunk-injected or sprayed compounds for apple scab control. * DFH: trunk diameter at 30 cm height. ** Maximum allowed seasonal dose per 0.405 ha based on EPA registration in USA. PH was injected undiluted. DC doses were injected with 520 ml of water per tree. 4. CONCLUSION • Timing of injections, compound formulations, and doses need to be further optimized to achieve better apple scab control. • Fruit residues after injection largely declined probably due to natural dysfunction of xylem in the fruit as it develops (Fig. 4A - D). • Fruit residue samples from same trees need to be collected in the second season following injection to determine any subsequent accumulation. Figure 4. (A) Fruit residue profiles and (E) leaf residue profiles of potassium phosphites (PH) in time. (B-D) Fruit residue profiles and (F-H) leaf residue profiles of difenoconazole + cyprodinil (DC) in time. Error bars represent standard error of the mean (SEM). Treatments Active ingredient Dose Dates of injection(s) or sprays in 2012 in 2013 Fall PH: mono- and di- potassium salts of phosphorous acid 45.8% (Phosphojet, (Arborjet Inc., Woburn, MA, USA) 5.17 ml/ 25.4 mm of DFH* 11 October - - Spring 5.17 ml/ 25.4 mm of DFH - 21 April - Fall + Spring 2 x 5.17 ml/ 25.4 mm of DFH 11 October 21 April - Spring + Spring 2 x 5.17 ml/ 25.4 mm of DFH - 21 April 22 May Sprays 9 x 1893ml/ 0.405 ha on 1, 8, 16, 21, 31 May and 5, 11, 19, 26 June 2013 Fall DC: difenoconazole 8.4% + cyprodinil 24.1% (Inspire Super, Syngenta AG, Basel, Switzerland) 7 ml/ tree** 11 October - - Spring 7 ml/ tree - 21 April - Fall + Spring 2 x 3.5 ml/tree 11 October 21 April - Spring + Spring 2 x 7 ml/ tree - 21 April 22 May 5 x 355 ml/ 0.405 ha on 1, 8, 16, 21, 31 May 2013 Sprays Water Injected Control - 500 ml/ tree 11 October 21 April 22 May 5. REFERENCES Aćimović S., VanWoerkom A., Garavaglia T., Vandervoort C., Wise J., Sundin G. (2013): Control of apple scab (Venturia inaequalis) using trunk injection of biopesticides and fungicides in apple trees. Phytopathology 103, Sup. 2, S2.2. Aćimović S., Zeng Q., McGhee G., Sundin G., Wise J. (2015): Control of fire blight (Erwinia amylovora) on apple trees with trunk-injected plant resistance inducers and antibiotics and assessment of induction of pathogenesis-related protein genes. Frontiers in Plant Science 6, 16. CONTROL OF APPLE SCAB (Venturia inaequalis) BY TRUNK-INJECTED FUNGICIDES AND SAR INDUCING POTASSIUM PHOSPHITES WITH RESIDUE PROFILES IN APPLE FRUIT AND LEAVES Srđan Aćimović 1 , Thomas Garavaglia 1 , Christine Vandervoort 1 , Dana Aćimović 2 , John Wise 3 and George Sundin 1 1 Department of Plant, Soil and Microbial Sciences, 2 Department of Horticulture, 3 Department of Entomology Michigan State University, East Lansing, MI, USA Figure 2. (A) QUIK-jet system used to inject low volume PH treatments and (B) Tree I.V. system used to inject high volume DC treatments into apple tree trunks through 4 cardinally oriented, drilled injection ports per tree shown in (C) (⌀ 9.5 mm x 25.4 mm) (Arborjet Inc., USA). Each port was sealed by plastic- silicone Arborplug no. 4 shown in cross-section (C) with silicone septum acting as one-way valve (red rectangle). (D) Arborplug cross-section with needle penetrating the white septum during injection. A B C D Figure 3. Control of apple scab on Mac Spur trees after trunk injection/s and sprays of potassium phosphites (PH) and difenoconazole + cyprodinil (DC) at different times. Apple scab control means within spur leaf, shoot leaf, and fruit graph sections followed by different letters are significantly different (p<0.05; t-test). Scab incidences in water injected control on spur leaves, shoot leaves, and fruit were 88.3, 94.4 and 95.5%, respectively. Each mean is based on 6 replicate trees. C D B C C A AB BC A B A A C AB B D G C D EF C D G C D F C A DE B -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 Spur leaves Shoot leaves Fruit Apple tree organ Apple Scab Control (%) Treatment / Time(s) of injection PH Fall PH Spring PH Fall + Spring PH Spring + Spring PH Sprays DC Fall DC Spring DC Fall + Spring DC Spring + Spring DC Sprays 3. 2. RESULTS - COMPOUND RESIDUES IN FRUIT AND LEAVES G H We calculated leaf scab incidences from 80 rated spurs and shoots per tree, and the fruit scab incidence from up to 100 fruit per tree (Fig. 3). At different times during the season we collected composite residue samples for HPLC-MSD analysis consisting of 40 buds or leaves per tree and 20 fruit in spring to a minimum 4 fruit per tree in the summer (Fig. 4).