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I. DALAPON (DOWPON) 



Dalapon applied at the rate of 10 pounds per acre gave the best grass control 

 of all the materials used in 1962. Although the control with 5 pounds of dalapon 

 was not as satisfactory, this rate gives a greater margin of safety because of the 

 tendency to overdose. 



Good grass control v;as obtained in June and July when it was 18 to 24 inches 

 high. Although the grass was killed, it remained standing and constituted an ex- 

 cellent mouse cover. It is recommended that tall grass be mowed and allowed to 

 make 8-10 inches of regrowth prior to treatment. 



When the sod cover is predominately grass, dalapon may be the only herbicide 

 necessary the first year of use. When weeds are present in the orchard, either 

 diuron or simazine can be added to the spray to control the seedling weeds that 

 might othen^ise move in where the grass was suppressed. Do not use the combina- 

 tion of dalapon and diuron on semi-dwarf or dwarf trees. 



H. AMIZINE 



Amizine is a mixture of simazine and amitrole. It has label clearance for 

 use in bearing apple orchards but must not be applied under trees after full 

 bloom. The label also states DO NOT ALLOW SPRAY ip CONTACT STEMS , FOLIAGE OR 

 TRUNKS OF TREES SPRAYE D. This is a serious limitation since it is difficult for 

 the grower to spray without accidental wetting of the trees. Therefore, it is 

 suggested that the use of amizine be limited to weed control under non-bearing 

 apple trees. 



Amizine at the rate of 7 pounds per acre gave good grass control but failed 

 to suppress all broadleaf weeds - vetch and milkweed. 



III. SIMAZINE 



Simazine 857, WP at the rate of 4 pounds per acre failed to give satisfactory 

 control of grass in several trials conducted in 1962. The treatments were applied 

 during May and June under trees having well-established grasses. This time of 

 application was used because many orchardists apply herbicides in May and June. 

 Simazine should be applied as a pre-emergence treatment and is not effective 

 when used at the 4 pound rate on established and growing vegetation. The best 

 use of simazine in our orchards, v/hich are grov/n under the sod-mulch system of 

 culture, is in combination with a label-approved contact weed killer such as 

 dalapon. The combination should eliminate many weeds which are likely to take over 

 where the grass has been subdued. Simazine stunts but does not eliminate all 

 sorrel, vetch, dandelions and other weeds. 



Trials have been established using Simazine under apple trees on October 15, 

 November 1 and as soon as the snow leaves the ground. 



IV. GRANULAR SIMAZINE 



Granular simazine has label clearance for use under non-bearing apple trees 

 at the rate of 50 to 75 pounds per acre. This material should be applied prior 

 to v;eed emergence. 



