Basil lovers are in luck this year. There are four new sweet basil varieties that are resistant to downy mildew. Downy mildew disease has affected basil for a decade now, destroying the leaves so much that gardeners have to throw away their infected basil plants.
The four new downy mildew resistant (DMR) basils developed by Rutgers University are Rutgers Devotion DMR, Rutgers Obsession DMR, Rutgers Passion DMR, and Rutgers Thunderstruck DMR.
Downy mildew disease was first reported in Florida in October 2007. It has since spread to field-grown and home-grown plants across the country. The disease appears as yellow leaves and a gray cotton appearance under the leaves (the spores). There is no treatment since these plants were meant to be eaten. Gardeners must throw the plants away at first sign to prevent infection of other plants.
Sweet basil has been more susceptible to the disease than Thai, lemon, lime, and the spice types of basil. This suggests that these other basils are genetically resistant to downy mildew. Researchers at Rutgers spent many years crossing sweet basil with these plants in order to provide the sweet basil with the same resistant genetic makeup. These basils were developed through traditional crossbreeding efforts, not genetic engineering. The four Rutger varieties still look, grow, and taste like sweet basil and can be grown in the garden or in containers. There is the possibility that home gardeners may see some disease spores under the leaves and yellow discoloration on the upper side but all they must do is snip off these leaves. The entire plant does not have to be thrown out.
Basil is an annual herb, easily grown from seed. In the Washington DC metro area, start growing basil outside after the last frost, usually mid-May. Basil likes full sun, warmth, and well-drained soil. The plants can benefit from fertilizer mid-summer especially if they are being harvested often. Basil should be harvested or pruned to encourage branching and more foliage and to prevent flowering. Home gardeners can find the Rutgers Devotion DMR and Rutgers Obsession DMR from Johnny’s Selected Seeds, High Mowing Organic Seeds, and Stokes Seeds.
Photos courtesy of Rutgers’ New Jersey Agricultural Experiment Station.
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These basil crosses do not taste like genovese basil. They taste more like thai basil.
That is not surprising, they were developed by crossing the sweet basil with Mrihani, a resistant variety from Zanzibar