All rates of picloram, either alone or in combination with low rates of 2,4-D, effectively controlled broom snakeweed on a blue grama range in southeastern Wyoming. Picloram also eliminated the low amounts of plains pricklypear present among the dense stands of snakeweed. Blue grama was initially injured by the 0.5 and 1 lb/acre rates of picloram, but needle-and-thread was damaged only by the 1 lb/acre rate. This initial injury to the grasses had a renovating effect upon the range, and, in combination with the elimination of undesirable plants, resulted in notable range improvement as measured 5 years after treatment. The study illustrates how herbicides may be a useful tool for selective manipulation of rangeland vegetation.

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This study evaluated methods and established procedures for growing seedling trees to a predetermined uniform size. White ash (Fraxinus americana 'L.) Geed gathered in the fall from indigenous sources was placed in a cool-Moist environment for 90 days to break embryonic dormancy.Red maple (Acer rubrum L.) and silver maple (Acer saccharinum L.) were similarly obtained io the spring but did not require a cold treatment.Seeds --re germinated in vermiculite, a 1:1 peat-perlite mixture, and washed ;a sand in the greenhouse and i a growth chamber. Following emergen the seedlings were grown for various periods in a growth chamber in nULtIent culture as well as In the above media in the greenhouse under supplementary light.in zontraat, dcrmant Anh and maple seedlings were obtained comnercially and exposed to various photoperiods.Dvylengths of 16 and 20 hourb were used in Llie growth chamber studies. Greenhouse photoperiods cf 16, 20, and 24 hours were achieved by supplementing the natural day of 10 to Ii hours with increments of fluorescent or incandescent light.The solution culture system is the only practical method that provides the opportunity for analyses or autoradiography of both foliag,-and roots. The optisuwm procedure evolved here was to germinate seed in vermiculite and transplant into individual pots of vermiculite, initially saturated with Hoagland's nutrient solution, when the seedlings were about 4 cm tall. After attaining a height of 20 to 25 cm, the seedlings were transferted to aerated solution culture and were considered ready for experimental use after 2 to 3 days of acclimatization.The environmental parameters were 25±3 C, 60±15% RH, and a 16-hour photoperiod of 1,000±300 ft-c.Wheri grown from seed, ash ard silver maple required 5 weeks to reach the optimum height of 20 to 25 cm; red maple required 8 to 9 weeks. We have successfully grown trees in solution culture in l-quart pots fo. 2 months with no special requirements other than periodic replenishment of the solution. The only limitation to growth of larger trees would be the need for physical support. For research, the use of uniform plants within a test population is very important to reduce inherent variability that could mask or attenuate any measured response resulting fron an imposed treatment. CONTENTSPresent m-tiaods of growing I-to 2-year-old tret 2 seedlings in soil under greenhouse conditions have not always produced desirable trees. Because many experiments require the utilization of the entite tree, including intact root systems, soil culture methods are not satisfactory.A variety of soilless culture Cechiiques have been described in the literature.Seedling trees have been grown in sph&:num moss soaked in nutrient solution,** perlite irrigated with nutrient solution,** and in aerated nutrient culture.1'a However) we found eýaLh of these methods had certain limitations.Perry and Upchurch 3 have described a method used for maple and ash.Seeds were germinated on wet paper towels, planted in a mixture of sand, peat, and soil (1:1...