Phytophthora disease (Phytophthora capsici), known as damping off on seedlings, seedling death, leaf blight, or fruit rot on mature plants, is an annual problem with home and commercial gardeners. This disease can quickly wipe out seedlings or infect plants in the field, reducing the quality and quantity of the yield.
Now researchers at the University of Illinois have shed a different light on
a new safe technique to prevent this disease. In trials, 4-week-old seedlings of pepper, tomato, and pumpkin were infected with Phytophthora disease and grown under one of three conditions: natural daylight, natural daylight with round-the-clock red light, and round-the-clock white light. Researchers found that seedlings exposed to round-the-clock red light for 4 weeks had significantly less disease than the other two treatments. After 14 days 78 to 100 percent of the white light and natural light seedlings died, while only 21 to 36 percent of the red light-treated seedlings died. It seems the benefits extend beyond the seedling stage. Red light-treated peppers transplanted in the field appear to have less disease than normal seedlings. However, more research is needed to confirm the field results.
Gardeners can use this technique at home simply by buying red lights found in lighting and hardware stores and keeping them on while they grow their seedlings under grow lights.