Nitric Acid and Benomyl Stimulate Rapid Height Growth of Longleaf Pine
Rapid height growth of longleaf pine seedlings, important to production of uniform, even-aged stands, can be promoted by controlling brown-spot needle blight and weed competition, and by increasing soil fertility. Root systems of container-grown longleaf pine seedlings were dip-treated in either benomyl/clay mix (10 percent a.i. benomyl) or clay control and planted in scalped rows that had been treated with various levels of nitric acid (0, 4, or 8 percent). After one growing season in the field, seedlings were evaluated for survival, brown spot infection, and vigor; plots were evaluated for weed competition. The benomyl root-dip treatment improved seedling survival, controlled brown spot infection, and promoted growth of outplanted seedlings in the first year. For the same period, treatment of soil with nitric acid improved seedling survival and vigor and significantly reduced the amount of competing vegetation. The combined use of benomyl and nitric acid resulted in the most rapid height growth.