Biological and Biopesticide Controls
Maintain large, active beneficial populations
Many soil bacteria and fungi can be antagonistic to root rot fungi. For example, a fungus called Trichoderma has been seen to reduce soil-borne disease infections. In general, additions of organic matter such as compost, grass clippings, and other material provide a food source for the soil food web helping to maintain large active populations of beneficial antagonists.
Biopesticides and biological pesticides. Biopesticides are certain types of pesticides derived from natural materials, such as animals, plants, bacteria, and certain minerals. One group of biopesticides are biologicals. Biologicals are composed of beneficial microorganisms, including specialized fungi, bacteria, and actinobacteria (filamentous bacteria) that are used against fungi and bacteria that cause plant diseases. Use of biopesticides (including biologicals) applied as a pre-plant dip or through the dripline on newly planted trees may help defend young trees from soil-borne disease infection. Efficacy data on biopesticides to date is limited. Some examples of biopesticides include:
- Streptomyces lydicus (Actinovate) (Gardener 2002)
- Trichoderma (Bio-TAM) (Smith 1990)
- Bacillus amyloliquefaciens (Double Nickel, Triathlon)
- Bacillus subtillus (Fungisei, Prevont, Serenade) (Utkhede, Sholberg, and Smirle 2000)
Note that only select fungicide active ingredients are effective on oomycetes such as Phytophthora since they are not true fungi, but rather water molds. Always read and check the label before using a chemical control.
Some studies have shown that soaking dormant trees before planting in a fungicide solution can result in increased root and shoot growth when plants are grown under conducive conditions and the pathogen is present (Jeffers 1992).
Treatment of the root zone
- Metalaxyl (MetaStar2E) at 2 gal/acre or 6 fl oz/1000 sq ft. Treat the entire root zone; do not concentrate near the base of the tree. Group 4 fungicide. 48-hr reentry (Bielenin and Jones 1988; Türkölmez and Derviş 2017).
- Mefenoxam (RidomilGoldSL) at 2 quarts/acre in sufficient water to move it into the root zone. Treat the entire root zone; do not concentrate near the base of the tree. Will not revitalize trees with moderate to severe symptoms. Group 4 fungicide. 48-hr reentry (Adaskaveg 2011).
Trunk and root-zone sprays
- Phosphorus acid, Mono-and di-potassium salts (Agri-Fos, Alude, Fosphite, Oxiphos, Phostrol, Rampart). Do not combine with a copper-spray program for control ofother diseases. Rampart can also be trunk injected. Group 33 fungicide (Flett 1996).
- Fosetyl AL (Aliette WDG) for bearing and non-bearing apples. For cherry non-bearing trees only. Do not control with a copper spray program. Group 33 fungicide (Utkhede and Smith 1991).
Adaskaveg, J.E. 2011. “Efficacy and timing of fungicides, bactericides, and biologicals for deciduous tree fruit, nut, strawberry, and vine crops.” Department of Plant Pathology, University of California Davis.
Bielenin, A. and Jones, A. L. 1988. “Efficacy of sprays of fosetyl-Al and drenches of metalaxyl for the control of Phytophthora root and crown rot of cherry.” Plant Disease no. 72:477-480.
Carisse, O., and S. Khanizadeh. 2005. “Relative resistance of newly released apple rootstocks to Phytophthora cactorum.” Canadian Journal of Plant Science no. 86:199-204.
Flett, S. 1996. “Developing safe foliar spraying of phosphonic acid to control peach and apple Phytophthora.” Project AP253, Final Report, Horticultural Research and Development Corporation, New South Wales.
Gardener, B. B. M. 2002. “Biological control of plant pathogens: research, commercialization, and application in the USA.” Plant Health Progress. doi:10.1094/PHP-2002-0510-01-RV.
Jeffers, S. N. 1992. “Preplant root treatments to reduce the incidence of Phytophthora species on dormant apple rootstocks.” Plant Disease no. 76:12-19.
Mazzola, M. 2017.
Robinson, T.L., G. Fazio, H.S Aldwinkle, S.A. Hoying, and N. Russo. 2006. “Field Performance of Geneva Apple Rootstocks in the Eastern USA.” Sodininkeyste IR Darzininkyste no. 25 (3):181-191.
Smith, V. L., Wilcox, W.F., and Harman, G.E. 1990. “Potential for biological control of Phytophthora root and crown rots of apple by Trichoderma and Gliocladium spp.” Phytopathology no. 80:880-885.
Thomidis, T. Michailidis, Z. 2002. “Preliminary evaluation of nine fungicides for control of Phytophthora cactorum and P. citrophthora associated with crown rot in peach trees.” Phytoparasitica no. 30:52-60.
Türkölmez, S. and Derviş, S. 2017. “Activity of metalaxyl-m+mancozeb, fosetyl-al, and phosphorous acid against Phytophthora crown and root rot of apricot and cherry caused by Phytophthora palmivora.” Plant Protect. Sci. no. 53:216-225.
Utkhede, R.S, P.L. Sholberg, and M.J. Smirle. 2000. “Effects of chemical and biological treatments on growth and yield of apple trees planted in Phytophthora cactorum infected soil.” Canadian Journal of Plant Science no. 23:163-167.
Utkhede, R.S. and Smith, E.M. . 1991. “Effects of fosetyl-al, and Enterobacter aerogenes on crown and root rot of apple trees caused by Phytophthpora cactorum in British Columbia.” Plant Disease no. 75:406-409.
Wilcox, W. F. 1992. “Phytophthora root and crown rots. Phytophthora spp. (deBary).” Tree Fruit Crops-Cornell Cooperative Extension-Disease Identification no. Sheet No. 7.
Yamak, F., T. L. Peever, G. G. Grove, and R. J. Boal. 2002. “Occurrence and identification of Phytophthora spp. pathogenic to pear fruit in irrigation water in the Wenatchee River Valley of Washington State.” Phytopathology no. 92 (11):1210-1217. doi: 10.1094/phyto.2002.92.11.1210.
WSU Tree Fruit Extension Specialist
TFREC Wenatchee, WA
1100 N Western Ave.,
Wenatchee, WA 98801
Use pesticides with care. Apply them only to plants, animals, or sites listed on the labels. When mixing and applying pesticides, follow all label precautions to protect yourself and others around you. It is a violation of the law to disregard label directions. If pesticides are spilled on skin or clothing, remove clothing and wash skin thoroughly. Store pesticides in their original containers and keep them out of the reach of children, pets, and livestock.
YOU ARE REQUIRED BY LAW TO FOLLOW THE LABEL. It is a legal document. Always read the label before using any pesticide. You, the grower, are responsible for safe pesticide use. Trade (brand) names are provided for your reference only. No discrimination is intended, and other pesticides with the same active ingredient may be suitable. No endorsement is implied.
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