![]() ![]() Sometimes air currents can spread the pathogen’s spores from field crops into greenhouses. “In the case of transplant production, sometimes the seed can be infected, which can immediately become a problem. We do have a few large controlled environment growers who sell transplants to retailers and field growers. North Carolina has more medium- to small-size field basil growers. “There aren’t as many field growers of basil and there is not as large acreage as in other states like in Florida. “I work with both controlled environment growers and field growers,” Quesada-Ocampo said. North Carolina State University plant pathologist Lina Quesada-Ocampo said there is not a lot of basil production in her state, but there are a number of controlled environment growers who produce a substantial number of basil transplants. This allows us to plant a month earlier and harvest a month later.” An early symptom of basil downy mildew includes leaf sections that are chlorotic. “The season in California is about two months longer. The season is long enough in Illinois so that we can begin harvesting in July and finish harvesting during the first week of October. “We have to wait until May to plant basil in Illinois. “We normally don’t use transplants,” DeYoung said. Growers in these states expect to deal with the disease all the time.” The basil crops produced by Van Drunen Farms and Golden State Herbs are direct seeded. “The pathogen has become established in Florida and other southern states and can overwinter there. “Contaminated seed was probably how the pathogen was first introduced into Florida,” Hausbeck said. This typically happens through wind-dispersed spores in southern plantings and also through the planting of downy mildew contaminated seed. Michigan State University plant pathologist Mary Hausbeck said in her state and other northern states, the pathogen cannot survive outdoors during the winter and must be introduced into a field. In warmer climates the basil downy mildew pathogen can overwinter. ![]() ![]() One of the worst outbreaks I’ve seen of basil downy mildew occurred in southern California, but it occurred much later in the year.” Environmental conditions that favor downy mildew don’t usually start there until mid-September and then the disease can occur. “In California we grow in the southern desert area. ![]() Photos courtesy of Hort Americas and Van Drunen Basil grown in controlled environments and outdoors are susceptible to downy mildew, which can cause major crop losses. The environmental conditions at that time are ideal for downy mildew. In Illinois the disease usually occurs in July. “Illinois has humid and cool temperatures that the downy mildew pathogen ( Peronospora belbahrii) likes. “The only place other than Illinois where environmental conditions are more conducive to downy mildew development is in Florida,” DeYoung said. Van Drunen Farms along with its sister company Golden State Herbs in California grow about 700 acres of basil outdoors. As long as we spray on time we can manage the disease.” For conventionally-grown crops, if we do a good job with our spray program we can protect the crop. “Once an organic crop is infected, the disease moves right across the field defoliating the plants. “For organic basil crops, downy mildew can be quite devastating and usually results in total crop loss that happens in just a few days,” said Alan DeYoung, director of ag research and development at Van Drunen Farms in Momence, Ill. Whether basil is grown in controlled environment structures or outdoors, downy mildew can be a destructive disease of this crop. Photos courtesy of Hort Americas and Van Drunen Farms Resistant varieties and additional fungicides can assist growers in protecting their basil crops from downy mildew infection. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |