Lack of winter chilling (480 hrs. at or below 7.2°C by 02/28/89) occurred along Alabama's Gulf Coast in the winter of 1988-89. Varieties requiring 650 hours of chilling or more were under stress. To evaluate hydrogen cyanamide (HC), a product used world wide to replace part of some fruit plants chilling req., a study was conducted along the Gulf Coast using Bicentennial (700 hr.), Sentinel (850 hr.) and Loring (900 hr.) peach varieties. Full tree sprays (applied to drip with handgun) using 0, .5 and 1% a.i. plus .25% × 77 were applied 03/01/89. Fruit buds were dormant to slight swell when sprayed. HC greatly enhanced rate and % of leaf bud break at the 1% conc., for all varieties. Rate and % of flowering were significantly increased at 1% conc. in Loring and Sentinel but nearly all fruit dropped. Flowering, yield and fruit size of Bicentennial-were significantly improved at .5 and 1% conc. HC was effective in replacing lack of chilling in this variety.
Arlie A. Powell and Ed Tunnell
Arlie A. Powell and Ed Tunnell
It has been shown that the `Hayward' kiwifruit requires ≈1000 chilling hours for satisfactory production of female flowers, leading to full cropping in the southeastern United States. Part of the area along the Gulf Coast frequently suffers from inadequate winter chilling, resulting in poor cropping of `Hayward'. Studies were conducted over a 4-year period in a mature `Hayward' planting near the Gulf Coast to evaluate the efficacy of hydrogen cyanamide sprays in replacing lack of chilling and improving cropping. Rates of 2%, 3%, and 4% (v/v) of 50% Dormex significantly increased yield, with the highest rate providing the maximum yield. Fruit size and overall fruit quality from Dormex treatments were good. Dormex sprays performed quite well when only 600 to 700 chilling hours were received in the test area.
Arlie A. Powell, Scott Goodrick, Ed Tunnell, and Richard Murphy
Inadequate winter chilling periodically becomes a serious problem for the commercial peach industry in the Southeast, especially along the Gulf Coast. A number of countries around the world are using hydrogen cyanamide (Dormex-SKW) to replace lack of chilling in peaches and other fruit plants. Studies were conducted over 3 years (1990-1992) to evaluate the effects of hydrogen cyanamide on replacing lack of winter chilling in 'Ruston Red' peach, (850 hour chill requirement). Findings indicated full tree sprays in early fall and late winter (after buds had become active) caused excessive bud thinning and crop reduction. Applications made when 65 to 85% of chilling requirement was satisfied (no visible bud activity) were very effective at concentrations of 0.5 to 1.0% V/V of 49% Dormex. Rates above 2% were very toxic causing crop loss. Dormex effectively replaced a shortage of 265 chilling hours of 'Ruston Red' during one season resulting in full cropping while controls failed to crop.
Arlie A. Powell, James Witt, William Dozier Jr., Scott Goodrick, Ed Tunnell, and Richard Murphy
Lack of winter chilling periodically becomes a serious problem for commercial peach producers in the Southeast, especially along and near the Gulf Coast areas. Studies were conducted over 3 years (1989-1991) to evaluate the effects of hydrogen cyanamide (Dormex - SKW) on replacing lack of winter chilling in 7 varieties of peaches.
Initial findings using whole tree sprays to point of runoff indicated a problem with efficacy and phytotoxicity. A combination of hydrogen cyanamide rates (0, .5, 1, 2 and 4% V/V) and timings (0, 25, 50 and 75% of chilling level) were evaluated in 1991. Rates above 2% were phytotoxic. Rates of 0.5 to 1.0% were safe and effective when applied at 75% chilling.