Articles
Investigating rootstock susceptibility and new Oomycota fungicides for the management of Phytophthora crown and root rot of pistachio in California
Article number
1406_60
Pages
427 – 434
Language
English
Abstract
Historically, Phytophthora crown and root rot was considered a minor disease of pistachio in California.
However, in recent years our laboratory has reported an increase of pistachio orchards with severe cases of the disease, particularly in areas with marginal soil conditions including high-saline and heavy-clay soils.
Phytophthora crown and root rot was commonly associated with pistachio trees planted on the industry standard UCB1 clonal and seedling rootstocks.
The recent emergence of Phytophthora diseases in pistachio orchards represents a serious threat to the industry, thus raising the need for control strategies.
Selection of a resistant rootstock is the first step toward sustainable management of soil-borne diseases.
Thus, the susceptibility of pistachio rootstocks UCB1, PG1, and Platinum against Phytophthora niederhauserii, P. mediterranea, and P. taxon walnut was investigated.
Susceptibility was assessed through stem and soil inoculations in potted plants under greenhouse and natural conditions.
Susceptibility was evaluated by lesion length, percent root mass loss, percent crown rot incidence, and plant-death ratio following artificial inoculations of the pathogens.
Results from these studies indicated Platinum rootstock as the most tolerant rootstock currently available to California pistachio growers.
Chemical treatments of systemic fungicides can also be implemented to manage Phytophthora crown and root rot.
Fungicides tested in this study included potassium phosphite, and mefenoxam as well as the new fungicides ethaboxam, fluopicolide, mandipropamid, and oxathiapiprolin.
Mean effective concentration values to inhibit mycelial growth by 50% for mefenoxam, oxathiapiprolin, mandipropamid, ethaboxam, fluopicolide, and phosphite were 0.0621, 0.0002, 0.007, 0.064, 0.126, and 66.10 μg mL-1, respectively, for P. mediterranea; 0.1667, 0.0003, 0.0105, 0.090, 0.102, and 34.60 μg mL-1, respectively for P. niederhauserii; and 0.0983, 0.0003, 0.0212, 0.174, 0.142, and 68.61 μg mL-1, respectively for P. taxon walnut.
Field studies to determine the most effective products for the management of Phytophthora crown and root rot of pistachio are underway.
However, in recent years our laboratory has reported an increase of pistachio orchards with severe cases of the disease, particularly in areas with marginal soil conditions including high-saline and heavy-clay soils.
Phytophthora crown and root rot was commonly associated with pistachio trees planted on the industry standard UCB1 clonal and seedling rootstocks.
The recent emergence of Phytophthora diseases in pistachio orchards represents a serious threat to the industry, thus raising the need for control strategies.
Selection of a resistant rootstock is the first step toward sustainable management of soil-borne diseases.
Thus, the susceptibility of pistachio rootstocks UCB1, PG1, and Platinum against Phytophthora niederhauserii, P. mediterranea, and P. taxon walnut was investigated.
Susceptibility was assessed through stem and soil inoculations in potted plants under greenhouse and natural conditions.
Susceptibility was evaluated by lesion length, percent root mass loss, percent crown rot incidence, and plant-death ratio following artificial inoculations of the pathogens.
Results from these studies indicated Platinum rootstock as the most tolerant rootstock currently available to California pistachio growers.
Chemical treatments of systemic fungicides can also be implemented to manage Phytophthora crown and root rot.
Fungicides tested in this study included potassium phosphite, and mefenoxam as well as the new fungicides ethaboxam, fluopicolide, mandipropamid, and oxathiapiprolin.
Mean effective concentration values to inhibit mycelial growth by 50% for mefenoxam, oxathiapiprolin, mandipropamid, ethaboxam, fluopicolide, and phosphite were 0.0621, 0.0002, 0.007, 0.064, 0.126, and 66.10 μg mL-1, respectively, for P. mediterranea; 0.1667, 0.0003, 0.0105, 0.090, 0.102, and 34.60 μg mL-1, respectively for P. niederhauserii; and 0.0983, 0.0003, 0.0212, 0.174, 0.142, and 68.61 μg mL-1, respectively for P. taxon walnut.
Field studies to determine the most effective products for the management of Phytophthora crown and root rot of pistachio are underway.
Authors
A.I. Hernandez-Rosas, R.J. Frias, F.P. Trouillas
Keywords
fungicide efficacy
Groups involved
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