Dr. A. James Downer Ph.D.

Advisor
Cooperative Extension Ventura County669 County Square Drive, #100
Ventura, CA 93003-5401
(805) 645-1458
ajdowner@ucanr.edu

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)
- Ornamental Crops, Landscape and Turf
- Aquatic Plants
- Ornamentals / Landscape / Turf - Other
- Ornamentals / Landscape / Turf - General
- Arboreta and Botanical Gardens
- Bedding / Garden Plants
- Bulbs, Corms, Rhizomes and Tubers
- Cut Flowers, Foliage and Greens
- Ground Covers
- Landscape - General
- Potted Plants
- Trees - Ornamental / Landscape / Shade
- Turf / Sod
- Woody Shrubs and Ornamental Vines
- Parks and Urban Green Space
- Horticulture
- Plants and Their Systems
- Basic Plant Biology
- Pathogens and Nematodes Affecting Plants
- Biological Control of Pests Affecting Plants
- Integrated Pest Management Systems
- Soil, Plant, Water, Nutrient Relationships
- Master Gardeners
- Sustainable Natural Ecosystems
- Endemic and Invasive Pests and Diseases
- Water Quality, Quantity, and Security
- Safe and Secure Food Supplies
- Healthy Families and Communities
- Sustainable Food Systems
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.
ANR Workgroup Associations
- Floriculture and Nursery - Member
- Landscape and Urban Horticulture - Member
- Nematology - Member
- Oak Woodland Conservation - Member
- Pest Management in ANR - Member
- Plant Pathology - Member
- Waste Management and Compost - Member