Strawberry Root Rot Caused by Verticillium Fungus
Managing Verticillium Wilt in Strawberry Plants
Verticillium wilt, a common disease affecting strawberry plants, is caused by the soilborne fungus Verticillium albo-atrum. This fungus can infect approximately 300 different host plants, including strawberries, and can survive in soil for 25 years or longer.
Under favorable environmental conditions, the fungus germinates and produces threadlike fungal structures (hyphae). These hyphae can penetrate root hairs directly or through breaks or wounds in the rootlets, initiating the infection process. Cool, overcast weather interspersed with warm, bright days is favorable for the development of Verticillium wilt.
The first symptoms of Verticillium wilt in new strawberry plantings often appear around the time runners begin to form. On infected plants, the outer and older leaves droop, wilt, turn reddish-yellow or dark brown at the margins and between veins. As the disease progresses, few new leaves develop, and those that do tend to be stunted and may wilt and curl up along the midvein.
As fungal colonies get older they produce microsclerotia in infected host tissue. These black, speck-sized bodies can remain viable in the soil for many years, ensuring the persistence of the fungus.
Effective control methods for Verticillium wilt in strawberry plants include chemical soil disinfestation (soil fumigation), use of resistant plant varieties, good soil preparation, and irrigation management.
Chemical soil fumigation before planting has proven effective in controlling Verticillium wilt and other soil-borne diseases in strawberries, as studied in Britain and applied commercially. Fumigants like chloropicrin (the active ingredient in some soil fumigants) can suppress Verticillium pathogens in soil, creating a clean environment for healthy planting.
Implementing good soil preparation such as bed forming, drip irrigation tape installation, and proper poly covering helps establish optimal growing conditions that reduce disease pressure. Irrigation management is critical; avoiding overwatering and using drip irrigation rather than overhead watering helps minimize pathogen spread through surface water runoff.
Additionally, cleanliness and sanitation help prevent disease spread. Thoroughly cleaning tools with rubbing alcohol or disinfectants between rows prevents spreading fungal pathogens during propagation or maintenance.
While resistance varieties aren't explicitly mentioned in the research for strawberry Verticillium wilt, resistance or tolerant rootstocks or cultivars are a common strategy for Verticillium wilt control in other crops and may be relevant for strawberry breeding programs. Several old and new cultivars have natural resistance to the Verticillium fungus, including June-bearing varieties such as Allstar, Catskill, Delite, Earliglow, Guardian, Lester, Rechief, Scott, Sunrise, Surecrop, and Tennessee Beauty, as well as the everbearing varieties Tribute and Tristar.
In summary, soil fumigation combined with good irrigation practices and sanitation is the most effective current approach to managing Verticillium wilt in strawberries, supported by scientific studies and commercial practice. It is important to note that many soils in Ohio contain the Verticillium wilt fungus, and only certified, disease-free strawberry plants of tolerant or resistant cultivars should be planted in Verticillium-infested soil. New varieties are constantly being developed and released, so checking with your nursery or local Extension educator to see if resistance to Verticillium wilt and other diseases is available in new varieties is recommended.
Soil fumigation before planting, combined with good irrigation practices and sanitation, offers an effective approach for managing Verticillium wilt in strawberry plants, according to scientific research and commercial applications. The use of resistant plant varieties, particularly those with natural resistance to the Verticillium fungus, may also be relevant for strawberry breeding programs. Proper soil preparation like bed forming, drip irrigation installation, and poly covering can help establish optimal growing conditions that reduce disease pressure. Irrigation management is crucial, with avoiding overwatering and using drip irrigation instead of overhead watering being key in minimizing pathogen spread. Additionally, maintaining cleanliness and sanitation by cleaning tools with disinfectants between rows can prevent the spread of fungal pathogens during propagation or maintenance. As people age and manage chronic diseases like medical-conditions, prioritizing health-and-wellness, including proper nutrition, fitness-and-exercise, could help improve overall well-being.
