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Arlie A. Powell and Karl Harker

This multifaceted study was conducted over the past 6 years in Alabama to determine the efficacy of using hydrogen cyanamide to replace lack of chilling in peaches and to develop a working chilling model to allow proper timing of application. Several timings (0%, 25%, 50%, and 75% chilling accumulation) for each chilling level and rates (0%, 0.5%, 1.0%, and 2.0% v/v of 50% hydrogen cyanamide) were evaluated in commercial orchards using replicated studies. It was determined that for Dormex to be effective, 60% to 65% of chilling for the cultivar involved must be accumulated, accompanied by no bud activity beyond bud swell. Rates of 0.5% and 1% v/v of 50% work well with the latter preferred. A computer chilling model was developed to assist growers with proper timing of application.

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Arlie A. Powell and Karl Harker

It is always challenging to develop innovative Extension programs delivery methods. The development of a winter chilling model (Modified 45) for Alabama, the evaluation of a growth regulator (Dormex—hydrogen cyanamide) to replace lack of chilling in peaches and the establishment of a computerized weather program allowed us to create a superior expert program for grower application. Access through a personal computer is all that is required to monitor chilling accumulation and determine the most ideal time for application of Dormex (which is very critical). This information (formerly available from NWS) is now accessible through a private weather firm. The development of a chilling hour/heat unit (growing degree hour) for peaches is showing promise of providing growers still another useful product (via their PCs) in improving orchard management via better timing of practices.

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Arlie A. Powell, Karl Harker, Roger Getz, and Eugene H. Simpson

In order to provide timely weather information to county agents (CEA) and growers, a sophisticated user friendly weather information program was developed that provides over 900 weather files daily to users. This program uses a 420 Sun Server that automatically downloads files from the NWS office on the AU campus and makes them instantly available to CEA offices via the Extension Network. Growers may obtain information from CEAS or use their personal computers to access a “Weather Board”. A chilling/growing degree hour (GDH) model (mod. 45) has been developed for peaches that provides a good estimate of when rest is completed and allows prediction of phenological stages through flowering. This information assists growers with orchard management decisions. Studies with peaches were conducted using the chilling/GDH model to properly apply hydrogen cyanamide (Dormex) to replace lack of chilling. This work resulted in an effective application timing based on chilling accumulation and allowed development of a forecast model for grower use.