How to Manage Pests
UC Pest Management Guidelines
Symptoms of this virus disease resemble those of nutritional deficiencies and other abiotic disorders and can be difficult to diagnose and confirm in the field. Leaves of strawberry plants with pallidosis-related decline turn purple to red in color. New growth may appear in the center of plants with young leaves that remain green. Plants affected early in their development are often stunted. Diseased plants have greatly reduced fruit production, and roots are brittle with reduced numbers of small absorptive rootlets.
Outbreaks of pallidosis-related decline are usually associated with the presence of the greenhouse whitefly vector, Trialeurodes vaporariorum, as well as aphids that can transmit many of the other viruses associated with this disease. Disease can occur in the absence of whitefly, however, because some transplants may already be infected with whitefly-transmitted viruses before planting.
The presence of BPYV or SPaV alone or together will not cause this disease. For pallidosis-related decline to occur, strawberry plants must be infected with SPaV or BPYV as well as any of several non-whitefly transmitted viruses.
SPaV and BPYV are members of the genus Crinivirus. SPaV has a narrow host range and is primarily limited to strawberry and related species but can also infect a few common weeds. BPYV has an extensive host range and infects many plants in addition to strawberry, including cucurbits and numerous weeds common in coastal production areas. Confirmation of virus infection requires testing plant material with molecular or serological techniques. Interestingly, strawberry plants are usually symptomless if infected with only SPaV or BPYV. Increased field populations of the greenhouse whitefly have been correlated with increased disease incidence in coastal strawberry fields in recent years.
Other viruses such as Strawberry latent ringspot and Fragaria chiloensis latent viruses were recently identified in California strawberry plantings. Their potential roles in pallidosis-related decline, along with the importance of other non-whitefly transmitted viruses, are being examined.
When available, use transplants that are not infected with SPaV or BPYV. Control the greenhouse whitefly and aphid vectors as best as possible. Remove weeds, which may be virus reservoirs.
UC IPM Pest Management Guidelines: Strawberry