Sprinkler Rot (Phytophthora Fruit Rot)

Phytophthora spp

40 host plants

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

Fruit at or near soil level rots with brown, watery decay, especially in wet conditions from overhead irrigation practices. Use drip irrigation instead of sprinklers, improve site drainage around trees, and keep fruit off wet soil.

Reduce moisture around affected tissue by improving drainage and air circulation. Remove rotted material cleanly and dispose of it away from the planting area. Avoid wounding healthy tissue during cleanup, as fresh wounds create new entry points. If the problem keeps returning, evaluate whether the site is too wet or poorly drained for the species you are growing.

Quick Reference

Causal Agent
Phytophthora spp
Host Plants
40
Favorable Conditions
Overhead irrigation or sprinkler systems that wet fruit; contaminated irrigat...

Management

Vulnerability Window

Most critical during fruit development and ripening (June-August in the Puget Sound region) when overhead irrigation is used for summer cooling. Fruit susceptibility increases dramatically as harvest approaches. Risk highest when warm temperatures (65-75°F) coincide with fruit-wetting irrigation events. Minimal risk with drip irrigation or low-angle sprinklers that keep fruit dry. # Source: PNW Plant Disease Management Handbook

What Triggers Infection

Overhead irrigation or sprinkler systems that wet fruit; contaminated irrigation water carrying Phytophthora propagules; warm soil temperatures (65-75°F); saturated or near-saturated soil conditions; fruit wetting for even brief periods (1 hour minimum); late-season fruit approaching harvest (increased susceptibility). # Source: PNW Plant Disease Management Handbook - Phytophthora Fruit Rot

Cultural Controls

  • Use low-angle or microsprinkler heads, that do not let water wet fruit, under trees.
  • Drip irrigation can also be used.
  • Reduce the length of irrigation sets.

Host Plants (40)

Prunus americana Wild Plum American (Red) Plum August Plum, Goose Plum Prunus armeniaca Apricot Prunus avium Sweet Cherry Prunus besseyi Sand Cherry, Western Sand Cherry Prunus blireiana Blireiana Plum Prunus caroliniana Carolina Cherrylaurel American Cherrylaurel Prunus cascade Prunus cascade Prunus cerasifera Cherry, Plum Prunus cistena Purpleleaf Sandcherry Redleaf Sandcherry Cistena Sandcherry Cistena Plum Prunus dream Prunus dream Prunus emarginata Bitter Cherry, Wild Cherry, Quinine Cherry Prunus first Prunus first Prunus fruticosa Steppe Cherry, European Dwarf Ground Cherry, Mongolian Cherry Prunus glandulosa Dwarf Flowering Almond Prunus ilicifolia Hollyleaf Cherry, Holly-leaved Cherry Prunus laurocerasus Cherry, Laurel Prunus lusitanica Portugal Laurel Prunus maackii Amur Chokecherry Amur Cherry, Manchurian Cherry Prunus mume Japanese Apricotc Japanese Flowering Apricot Japanese Flowering Plum Prunus newport Newport Flowering Plum Prunus okame Okame Flowering Cherry Prunus padus European Birdcherry Common Birdcherry Prunus prostrata Rock Cherry, Mountain Cherry Prunus sargentii Sargent Cherry, Sargent's Cherry Prunus serotina Black Cherry, Rum Cherry Prunus serrula Birchbark Cherry, Paperbark Cherry, Tibetan Cherry Prunus serrulata Japanese Flowering Cherry Prunus snow Prunus snow Prunus subcordata Klamath Plum, Sierra Plum, Pacific Plum Prunus subhirtella Higan Cherry Prunus subhirtella var. autumnalis Autumn Flowering Higan Cherry Prunus tai Prunus tai Prunus virginiana Prunus virginiana Prunus virginiana var. demissa Western Chokecherry Prunus virginiana var. virginiana Common Chokecherry, Eastern Chokecherry Prunus yedoensis Yoshino Cherry, Somei-yoshino Cherry, Tokyo Cherry Pyrus calleryana Callery Pear Pyrus communis Common Pear Pyrus fauriei Pyrus fauriei Pyrus salicifolia Pyrus salicifolia