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Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

Dr. A. James Downer Ph.D.

Photo of Dr A. James Downer Ph.D.
Advisor
Cooperative Extension Ventura County
669 County Square Drive, #100
Ventura, CA 93003-5401
(805) 645-1458
ajdowner@ucanr.edu Create VCard

Links

Biography

BSc Cal Poly, Pomona, 1981 Botany/Ornamental Horticulture MSc Cal Poly, Pomona, 1983 Biology/Plant Pathology Ph.D. Univ. California Riverside, 1998 Plant Pathology

Education

Ph.D. Plant Pathology, UC Riverside. 1998

Specialty

Pathology of landscape ornamentals , Phytophthora Root Rot, Mulches, Potting soils, Palm horticulture, climate ready trees, arboriculture, Master Gardener Advisor.

Areas of Expertise (click to see all ANR academics with this expertise)

Bibliography

Peer Reviewed

  • Downer, A.J. and S. Swain and A. Crump (2020). Anthrcnose, UCIPM Pest Notes, Publiction # 7420.
  • Fescenko, A.; Downer, J. A.; Fescenko, I (2020). Persistence of remnant boreal plants in the Chiricahua Mountains, Southern Arizona. Global Ecology and Conservation. Elsevier. 23, 1-10.
  • Downer, A.J.; Karlik, J.F. (2019). A Comparison of Two Horsechestnut Street Tree Plantings in Kiev and Pripyat, Ukraine. Open J. Forestry. 9, 255-263.
  • Downer, A.J. and I. Lacan (2019). Armillaria UC IPM Pest Notes UCANR #74171. UCANR.
  • Karlik, J.F.; Downer, A.J. (2019). Comparison of Gamma Ray Dosimeters in a Field Study in the Chernobyl Exclusion Zone. J. of Air and Waste Man. 11, 1361-1367.
  • Takeuchi, T.; Downer, A.J. (2019). Lead absorption by radish is affected by soil texture and cultivar. Open J. Soil Science. 9:4, 65-74.
  • Downer, A.J.; Faber, B. (2019). Mulches for landscapes. ANR publication #8672.
  • Downer, A.J.; Faber, B. (2019). Non-chemical prevention of Armillaria mellea infection of Peach (Prunus persica). Plant Sci. and Phytopathology. 3, 50-55.
  • Downer, A.J.; Perry, E.J. (2019). Wood Decay Fungi in the landscape. ANR publication #74109.
  • Chalker-Scott, L; Downer, J (2018). Garden myth busting for Extension Educators: Reviewing the Literature on Landscape Trees. J. of the National Assn. Ag. Agents. 11:2. https://www.nacaa.com/journal/index.php?jid=885&fbclid=IwAR3fS2iKo8ibifQEDPUrG6UlcB8n-yUgOe6xx1y56MeAcLhP6ZoUkQbUQNg
  • Downer, J. (2016). Native Diseases of California Mediterranean Forest Angiosperms.T. Paine and F. Lieutier. Springer. 529-547.
  • Neila, S.; Akef, S.; Bouzaiane, O.; Kallali, H.; Aissa, N. Ben; M’Hiri, F.; Downer., N. Jedidi and J. (2015). Carbon and nitrogen mineralization in clay loam soil amended with different composts. Advances in Applied Ag. Science 03:20-34. Advances in Applied Ag. Science. 03, 20-34.
  • Downer, A.; Howell, A.; Karlik, J. (2014). "Effect of pruning on eight landscape rose varieties." Acta Horticulturae
  • Downer, A.; Hodel, D.; Matthews, D.; Pittenger, D. (2013). "Effect of fertilizer nitrogen source on susceptibility of five species of field grown palms to Fusarium oxysporum f. sp. carnariensis." Palms 57: 89-92.
  • Hodel, D.; Downer, A.; Pittenger, D. (2013). "Effect of leaf removal and tie-up on date palms transplanted in extremely hot, arid conditions." Palms 57: 72-78.
  • Hodel, D.; Downer, A.; Pittenger, D. (2013). "Effect of leaf removal and tie-up on water loss and estimated crop coefficients for juvenile trunkless containerized queen palms." Palms 57: 79-83.
  • Downer, A.; Hodel, D.; Pittenger, D. (2013). "Effect of leaf tie-up and pre-plant storage on growth and transpiration of transplanted Mexican fan palms." Palms 57: 58-63.
  • Hodel, D.; Downer, A.; Pittenger, D. (2013). "Effect of sand backfill on transplanted king, queen, and windmill palms." Palms 57: 63-66.
  • Bennett, P.; Bauske, E.; O'Connor, A.; Reeder, J.; Baush, C.; Kratsch, H.; Leger, E.; Callaghan, A.; Nitzsche, P.; Downer, A. (2013). "Farmers' Market, Demonstration Gardens, and Research Projects Expand Outreach of Extension Master Gardeners." HortTechnology 23: 411-415.
  • Downer, A.; Hodel, D. (2013). "Suitability of ground palm trunk tissues as a medium for growing potted plants." Palms 57: 67-71.
  • Khiari, L.; Neila, S.; Kouki, S.; Rejeb, A.; M'hiri, F.; Hajilaoui, M.; Fumio, M.; Hassen, A.; Jedidi, N.; Downer, A.J.; Ouzari, H. (2012) Control of Fusarium wilt of tomato caused by Fusarium oxysporum f.sp. lycoperscici using mixture of vegetable and Posidonia oceanica compost. Applied and Environmental Soil Science 11 DOI: 10.1155/2012/239639
  • Hodel, D.; Downer, A.; Pittenger, D. (2012). "Effect of container type on the nursery growth of kentia palms and king palms." Palms 56: 65-71.
  • Mayorquin, J.; Eskalen, A.; Downer, A.; Hodel, D.; Liu, A. (2012). "First report of multiple species of the botryosphaeriaceae causing bot canker disease of Indian laurel leaf fig in California." Plant Disease 96(3): 459.
  • Corkidi, L.; Merhaut, D.; Allen, E.; Downer, A.; Bohn, J.; Evans, M. (2011). "Effects of Mycorrhizal colonization on nitrogen and phosphorus leaching from nursery containers." HortScience 46: 1472-1479.
  • Pittenger, D.; Downer, A.; Hodel, D.; Mochizuki, M. (2009). "Estimating water needs of landscape palms in Mediterranean climates." HortTechnology 19: 700-704.
  • Downer, A.; Uchida, J.; Elliot, M.; Hodel, D. (2009). "Lethal palm diseases common in the United States." HortTechnology 19: 710-716.
  • Downer, A.; Hodel, D.; Mochizuki, M. (2009). "Pruning Landscape Palms." HortTechnology 19: 695-699.
  • Hodel, D.; Downer, A.; Mochizuki, M. (2009). "Pruning Landscape Palms." HortTechnology 19: 695-699.
  • Hodel, D.; Downer, A.; Pittenger, D. (2009). "Transplanting Palms." HortTechnology 19: 686-689.
  • Downer, A.; Crohn, D.; Faber, B.; Daugovish, O.; Becker, J.; Menge, J.; Mochizuki, M. (2008). "Survival of plant pathogens in static piles of ground green waste." Phytopathology 98: 574-554.
  • Faber, B.; Downer, A.; Holstege, D.; Mochizuki, M. (2007). "Accuracy varies for commercially-available soil test kits analyzing nitrate nitrogen, phosphorus, potassium and pH." HortTechnology 17: 358-362.
  • Crohn, D.; Faber, B.; Downer, A.; Daugovish, O. (2007). "Probabilities for survival of glassy-winged sharpshooter and olive fruit fly pests in urban yard waste piles." Bioresource Technology 99: 1425-1432.
  • Hodel, D.; Downer, A.; Pittenger, D. (2006). "Effect of leaf removal and tie-up on transplanted large Mexican fan palms (Washingtonia robusta)." Palms 50: 76-81.
  • Hodel, D.; Downer, A.; Pittenger, D. (2006). "Effect of leaf removal and tie-up on transplanted large Mexican fan palms (Washingtonia robusta)." Palms 50: 76-81.
  • Koike, S.; Daugovish, O.; Downer, A. (2006). "Sclerotinia stem and crown rot of celery, caused by Sclerotinia minor, in California." Plant Disease 90: 829.
  • Hodel, D.; Downer, A.; Pittenger, D.; Beaudoin, P. (2006). "The effect of amended backfill soils when planting five species of palms." HortTechnology 16: 457-460.
  • Daugovish, O.; Downer, A.; Faber, B.; McGiffen, M. (2006). "Weed survival in yardwaste mulch." Weed Technology 21: 59-65.
  • Downer, A.; Faber, B. (2005). "Effect of Eucalyptus cladocalyx mulch on establishment of California sycamore (Platanus racemosa)." Journal of Applied Horticulture 7: 90-94.
  • Corkidi, L.; Allen, E.; Merhaut, D.; Allen, M.; Downer, A.; Bohn, J.; Evans, M. (2005). "Effectiveness of four commercial mycorrhizal inoculants on the growth of Liquidambar styraciflua in plant nursery conditions." Journal of Environmental Horticulture 23: 72-76.
  • Dahlsten, D.; Dane, K.; Paine, T.; Sime, K.; Lawson, A.; Rowney, D.; Roltsch, W.; Andrews, J.; Kabashima, J.; Shaw, D.; Robb, K.; Geisel, P.; Chaney, W.; Ingels, C.; Bianchi, M.; Varela, L.; Downer, A.; Haviland, D.; Talor, G.; Keller, M. (2005). "Imported parasitoid helps control red gum lerp psyllid." California Agriculture 59: 229-234.
  • Hodel, D.; Pittenger, D.; Downer, A. (2005). "Palm root regeneration and implications for transplanting." Journal of Arboriculture 31: 171-181.
  • Pittenger, D.; Hodel, D.; Downer, A. (2005). "Transplanting specimen palms: a review of common practices and research-based information." HortTechnology 15: 128-132.
  • Corkidi, L.; Allen, E.; Merhaut, D.; Allen, M.; Downer, A.; Bohn, J.; Evans, M. (2004). "Assessing the infectivity of commercial mycorrhizal inoculants in plant nursery conditions." Journal of Environmental Horticulture 22: 149-154.
  • Daugovish, O.; Downer, A.; Becker, O.; Browne, G.; Duniway, J. (2004). "Mustard-derived biofumigation for vegetable crops and strawberries." Agroindustria 3: 5-8.
  • Valenzuela-Solano, C.; Crohn, D.; Downer, A. (2004). "Nitrogen mineralization from eucalyptus yard waste mulch applied to young avocado trees." Biology and Fertility of Soils 41: 38-45.
  • Hodel, D.; Pittenger, D.; Downer, A. (2003). "Effect of Leaf removal and tie up on juvenile transplanted canary island date palms (Phoenix canariensis) and queen palms (Syagrus romanzoffiana)." Palms 47: 177-184.
  • Downer, A.; Craigmill, A.; Holstege, D. (2003). "Toxic potential of oleander derived compost and vegetables grown with oleander soil amendments." Journal of Human and Veterinary Toxicology 45: 219-221.
  • Downer, A.; Faber, B.; Menge, J. (2002). "Factors affecting root rot control in mulched avocado orchards." HortTechnology 12: 601-605.
  • Dagit, R.; Downer, A. (2002). To prune or not to prune: recovery of Coast Live Oak after transplanting. 5th Oak Symposium (Proceedings), San Diego, CA, USDA Forest Service.
  • Downer, A.; Menge, J.; Pond, E. (2001). "Association of cellulytic enzyme activities in eucalyptus mulches with biological control of Phytophthora cinnamomi Rands." Phytopathology 91: 847-855.
  • Faber, B.; Downer, A.; Menge, J. (2001). "Differential effects of mulch on citrus and avocado." Acta Horticulturae 557: 303-307.
  • Downer, A.; Menge, J.; Pond, E. (2001). "Effects of cellulytic enzymes on Phytophthora cinnamomi Rands." Phytopathology 91: 839-846.
  • Downer, A.; Hodel, D. (2001). "The effect of mulching and turfgrass on growth and establishment of Syagrus romanzoffiana (Cham.) Becc., Washingtonia robusta H.Wendl. and Archontophoenix cunninhamiana (H.Wendl.)H. Wendl. & Drude in the landscape." Scientia Horticulturae 87: 85-92.
  • Dagit, R.; Downer, A. (1999). "Transplanted coast live oaks (Quercus agrifolia) in southern California." Journal of the International Oak Society 9: 145-150.
  • Downer, A. (1998). The effects of mulch on Phytophthora cinnamomi and Avocado Root Rot. Ph.D. Dissertation. University of California, Riverside, CA. 212.
  • Dagit, R.; Downer, A. (1997). Status of transplanted coast live oaks in Southern California. Symposium on Oak Woodlands: Ecology, Management and Urban Interface Issues (Proceedings), San Luis Obispo, CA, Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture.
  • Dagit, R.; Downer, A. (1996). Status of transplanted coast live oaks in Southern California. Symposium on Oak Woodlands: Ecology, Management and Urban Interface Issues (Proceedings), San Luis Obispo, CA, Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture.
  • Cudney, D.; Downer, A.; Gibeault, V.; Reints, J. (1995). "A non-disruptive technique for kikuyugrass control in cool season turf." California Agriculture 48: 24-28.
  • McGiffen Jr., M.; Greene, R.; Manthey, J.; Faber, B.; Downer, A.; Sakovich, N.; Aguilar, J. (1995). "Field tests of methanol as a crop yield enhancer." HortScience 30: 1225-1228.
  • Faber, B.; Downer, A.; Yates, L. (1993). "Inexpensive, hand-held moisture meters." HortTechnology 3: 195-196.
  • Cudney, D.; Downer, A.; Gibeault, V.; Henry, J.; Reints, J. (1993). "Kikuyugrass (Pennisetum clandestinum) management in turf." Weed Technology 7: 180-184.
  • Bellows, T.; Paine, T.; Gould, J.; Bentley, W.; Coviello, R.; Downer, A.; Elam, P.; Flaherty, D.; Goevca, P.; Koehler, C.; Molinar, R.; Perry, E.; Voegel, G. (1992). "Biological control of ash whitefly: a success in progress." California Agriculture 46: 27-28.
  • Downer, A.; Koehler, C.; Paine, T. (1991). "Biology and management of the eugenia psyllid (Trioza eugeniae Froggatt)." Journal of Environmental Horticulture 9(3): 137-141.
  • Downer, A.; Cudney, W. (1989). "Glyphosate doesn't harm tall fescue." California Agriculture 43: 13-14.
  • Armentrout, V.; Downer, A.; Grasmick, L.; Weinhold, A. (1987). "Factors affecting infection cushion development by Rhizoctonia solani on cotton." Phytopathology 77: 623-630.
  • Armentrout, V.; Downer, A. (1987). "Infection cushion development by Rhizoctonia solani on cotton." Phytopathology 77: 619-623.
  • Downer, A.; Koehler, C.; Svihra, P.; Molinar, R. (1987). "New psyllid pest of California pepper tree." California Agriculture 42: 30-32.
  • Armentrout, V.; Downer, A.; Nameth, S. (1986). "A simplified branching assay for Rhizoctonia solani." Mycologia 78: 657-663.

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