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Abstract
A large volume generator with a foam-producing rate of 130 ft3/min is described. The generator is based on a simple principle and could be easily adapted to a variety of field foam application requirements. A combination of 3 materials has been found that will form an economical, stable, nontoxic foam for insulating crops during freezing conditions. Field tests showed that the foaming materials and foam generator have the necessary characteristics for covering large acreages of temperature-sensitive crops.
Abstract
The cambium of both ‘Early Amber’ peach and ‘Sungold’ nectarine, Prunus persica L. Batsch gained cold hardiness from November through January even though day and night temperatures were above 15°C. Cultivars attained the greatest hardiness in January, surviving temperatures of -12°C. ‘Early Amber’ maintained its hardiness until just prior to bud break (February 8) and decreased thereafter. ‘Sungold’ remained somewhat resistant to cold until February 15 and gradually lost hardiness until March 8. Characteristically the low chilling cultivars reached an acclimation base higher than reported for cultivars adapted to higher latitudes.
Abstract
‘Early Amber’ peach and ‘Sungold’ nectarine (Prunus pérsica (L.) Batsch) growing in north central Florida acclimated sufficiently to cold to withstand −14° to −15°C although day temperatures were above 20° and night temperatures were above 7°. Rest and acclimation to cold in short chilling cultivars occur at higher temperatures than in long chilling ones. However, Florida cultivars also become acclimated to a lesser degree. Wood chips taken from the trunks of ‘Early Amber’ trees in January survived −10°C but were killed at −13°. Young trees were killed at −11° but survived −10° in January. Subsequent death of tissue occurs as a result of low temperature stress.
Abstract
A delay in flowering of up to 14 days was obtained in the 1974-75 and 1975-76 seasons with ‘Sungold’ and ‘Sunrich’ nectarines and ‘Flordagold’ peach [Prunus persica (L.) Batsch] by intermittent sprinkling when tree temperatures exceeded 18°C. Flowering and foliation was also hastened in 1974-75 on trees shaded with 55% saran cloth. Sprinkling did result in heavy bud abscission on certain cultivars. Shading and sprinkling lowered cambial temperatures by 5 to 10° and delayed harvest from 5 to 7 days.
Abstract
The climate of trees and vines is different from fields, meadows, and agronomic crops. These differences may be tied to the evolution of trees and vines, or they may be a peculiar result of man’s culture. Knowledge of the climate of trees and vines may be of assistance to the horticulturist in climatic modification.
Abstract
Foam was applied for frost protection to January planted cantaloupes (Cucumis melo L.) in the Lower Rio Grande Valley of Texas. Two planting configurations consisting of shallow trenches and conventional beds were compared to evaluate volume of foam required and durability. The trench planting technique increased the foam’s durability and reduced the volume approximately three-fourths. The cost of foam application to a low profile crop in the shallow trenches was approximately $74.00 per hectare. Leaf temperature in the foamed trenches was up to 12°C warmer than nonfoamed conventional beds.
Abstract
A modified Scholander pressure bomb was sensitive enough to detect significant differences in relative leaf water stress among ‘Orlando’ tangelo (Citrus reticulata Blanco × C. paradisi Mact) on several rootstocks. Leaf water potential for the rootstocks ranged from -7.9 bars for rough lemon (Citrus jambhiri Lush.) to -13.7 bars for those on trifoliate orange (Poncirus trifoliata Raf.). There was a diurnal pattern in leaf water stress. Modifications and procedures for the pressure bomb measurements are described.