CONTROL OF MINT NEMATODE WITH VYDATE
|Mint nematodes are
very sensitive to Vydate, and foliar as well as soil applications are generally effective
for control. Dipping foliage into a Vydate solution (equivalent to 2 lb a.i./A) for 30 sec
reduced populations 80% (90 days after treatment) when treatments were made 10 days
before, at the same time, or 30 days after nematodes were added to pots. A second
application 10 days later reduced populations an additional 15% (Jatala and Jensen, 1974).
Few studies have been conducted on the efficacy of Vydate on control of mint nematode in the field, but those completed also indicate dramatic improvement of mint performance. Late spring applications at 1/2, 1, or 1 1/2 GPA significantly increased oil yield by an average of 60%, but there was no difference between these rates. In addition, two and three applications of 1/2 GPA did not increase yield more than a single application (Table 1)(Pinkerton and Jensen, 1983).Table 1. Effect of Vydate 2L application rate (GPA - gallons per acre) on oil yield in field severely infested (1400/quart soil) with mint nematode (Longidorus elongatus). Modified from Pinkerton and Jensen, 1983).
Treatment Oil Yield (lb/A)
28 a (4)
Applications in winter (late February) or spring (mid-June) tended to provide greater increases in hay yield than fall (mid-November) treatments. Split applications at fall and spring, fall and winter, or winter and spring were equal to each other in performance and superior to a single application. In most instances, rates of 1/4 to 1 GPA provided equal control (Table 2).
After effective treatment, the suppressed nematode activity permits plants to regrow a vigorous root system with greater branching and deeper penetration of the soil. This rejuvenated root system is more effective at taking up water and nutrients, culminating in increased yields of hay and oil. However, this healthier root system is also an excellent environment for rapid growth of the remaining population. This accounts for the observation of higher nematode densities in late summer and the potential need for subsequent treatments to maintain stand vigor. Noticeable plant responses after treatment include taller and more vigorous foliage which is darker green in color (Pinkerton and Jensen, 1983).