Guide For Timing Dormex Sprays (Submitted by Dr. Arlie A. Powell, Extension Horticulturist, Auburn University) ------------------------------ The following will serve as a guide for timing spray applications: Table 1. Chilling information for use in applying Dormex to peaches in Alabama. ------------------------------------------------------------------------------- Chilling Accumulation Action Levels ------------------------------------------------------ Optimum Chilling Range Ideal Timing For Application For Application ------------------------------------------------------ Chilling Class As % of Chilling Hrs. As % of Chilling Hrs. of Variety Chill Req. (45F. or less) Chill Req. (45F. or less) --------------------------------------------------------------------- 650 65 to 85 425 to 555 75 490 750 65 to 85 490 to 640 75 565 850 65 to 85 550 to 725 75 640 950 70 to 90 665 to 855 80 760 --------------------------------------------------------------------- Special Info On Spraying Peaches In Al For Lack Of Chilling. ------------------------------------------------------------ Alabama and Georgia were fortunate in 1992 when EPA approved the use of a Section 18 to allow application of Dormex (hydrogen cyanamide) on peach trees suffering from lack of chilling. However, late cold in February provided adequate chilling in all areas except the Wiregrass and not much Dormex was applied. Another Section 18 has been submitted to EPA for approval of Dormex use in Alabama during 1993. Hopefully this request will be approved in time for application during February. If approved, growers should follow the label instructions very carefully for safe, effective use of this chemical. County Extension agents have information on where chemicals may be obtained. A number of important keys are given below to assist growers in understanding and using this growth regulator. A. Apply Dormex at a rate of 0.5 to 1.5% (volume/volume) plus a non-ionic surfactant at 0.25%. The preferred rate of 1.0% would consist of 1.0 gal of Dormex (49% a.i.) plus 1.0 quart of surfactant and 98.75 gals of water to prepare 100 gals of spray solution. B. The spray should be applied when 65 to 85% of the chilling requirement has been met and while fruit buds are still dormant (no visible activity). See other products, under the Fruit Growers Weather Information Menu, for more information on chilling hour accumulations and percent of requirement met in their area. C. Dormex should be applied to dormant trees as a complete tree spray to near the point of drip. Excessive wetting is not desirable or necessary. Depending upon tree size 50 to 100 gals of spray should be adequate per acre. (It isn't necessary to spray upper parts of trees that will be removed during pruning.) D. For optimum effectiveness and no phytotoxicity Dormex should be applied under sunny conditions such that sprays will dry in 15 to 30 minutes. Do not apply under misty/or foggy conditions or if such conditions or rain is forecast within 24 hours after application. (To be safe spray when no rain is forecast for at least one day after application.) Applying under these conditions may cause excessive thinning of fruit buds. Apply when current temperatures are between 50 to 75 degree F. Do not apply when current temperatures are below 40 degrees F., or if temperatures of 32 degrees or below are forecast for the next morning. E. Apply Dormex in combination with no other chemicals other than surfactant. Do not apply any pesticide (including oil spray) within one week before or one week after Dormex application. Special Safety Precautions & Chemistry Of Dormex ------------------------------------------------ Dormex (hydrogen cyanamide) is available in one formulation only, a blue liquid. It will not store well at room temperature but will remain in good condition for at least a year if refrigerated (35 to 40F.). Dormex is a moderately toxic chemical but not nearly as hazardous as pesticides such as parathion. However, special care should be exercised to ensure safe use of this chemical in the orchard. Protective clothing including head gear, etc. must be worn during mixing and application. No alcohol (see label) should be consumed for a number of hours before and following application. Non-target areas must not be sprayed and a non-sprayed buffer area must be maintained around the orchard to avoid problems with endangered or threatened species. Under aerobic soil conditions, hydrogen cyanamide degrades rapidly with a half-life of less than 1 day. Refer to the label and other Section 18 information for more detail on the particulars regarding safe use of Dormex in peach orchards.