For several reasons a trend has developed in many fruit growing areas 

 toward the application of residual herbicides later in the spring with a 

 postemergence contact herbicide. Growers are extremely busy in March and 

 April pruning, planting, fertilizing, pollinating, thinning, and spraying 

 for insects and diseases. Weather frequently is not favorable for spraying 

 herbicides. Delaying application is convenient. In addition, the marginal 

 crop safety of Sinbar^ and Karmex" on extremely coarse-textured soils low 

 in organic matter has led to the use of reduced rates. This has resulted 

 in reduced length of residual control. Delaying application from early 

 April until late May or early June can compensate for this reduced length of 

 control, but unfortunately results in ^ to 8 weeks of weed competition in 

 the spring when the trees are growing vigorously. Vigorous weed competition 

 in late April and May can reduce efficient utilization of annual spring fer- 

 tilizer applications (and water in dry years). 



Residual herbicides for summer annual weed control should be applied in 

 late fall or early spring. Maximum effectiveness is observed when applied 

 in November or late March to early April. At least 1/2 to 1 inch or rain is 

 needed to move the spring-applied herbicides into the soil and into contact 

 with weed seeds as they begin to germinate. Early application and rainfall 

 are more critical when using some of the more recently labeled herbicides, 

 including Devrinol^, Surflan", and Prowl^, which inhibit germination and 

 seedling emergence, than when using Sinbar^, Karmex^, or Princep^ which 

 affect photosynthesis. 



Growers who cannot efficiently apply herbicides in early spring and 

 growers with extremely coarse-textured low-organic-matter soils should con- 

 sider splitting their weed control program into 2 applications. Apply half 

 of the total rate of the annual grass herbicide plus an annual broadleaf 

 weed herbicide in November to provide weed control until early summer. 

 Apply the second half of the annual grass herbicide plus a different annual 

 broadleaf herbicide in late spring to control weeds until fall. Choose her- 

 bicide combinations based on weed species present or expected in each 

 orchard. 



Winter annual, biennial, and certain perennial broadleaves, including 

 horseweed, camphorweed, and dandelion, can be most effectively controlled by 

 anplying 2,'«-D in early spring or late fall. Two formulations, Hi-Dep" by 

 PBI-Gordon and Envy^ by Lilly-Miller, are labeled for use with stone fruits. 

 2,4-D can be tank-mixed with the residual herbicides applied at that time. 

 Sod strips between tree rows can also be treated with ?.,k-D to control 

 broadleaf weeds. Use care when applying 2,4-D as a growth regulator type 

 herbicide, because minute amounts of drift can seriously damage many 

 flowers, vegetable crops and grapes. Avoid using 2,'*-D in late spring and 

 summer after these sensitive crops are growing. 



Control hard-to-kill perennial broadleaf weeds in the orchard by spot 

 treating the weed with glyphosate (Roundup*^). Application timing is criti- 

 cal to obtain maximum translocation of the herbicides from the leaves where 

 it is absorbed into the extensive root systems of these weeds. The optimum 

 time of application depends on the weed species. Apply Roundup^ when the 



