Trees budded on the Brazilian rootstock `A-82' have a lower feeding preference by the primary vector of Phony peach disease over trees on `Nemaguard'; the southeastern industry standard rootstock. `A-82' budded trees have lower levels of infection of the xylem-limited bacteria Xylella fastidios a compared to `Nemaguard' budded trees.
The feasibility of using `A-82' in the industry was evaluated by budding `Flordaking' and `Flordaglobe' peach and `Sungem' and `Armking' nectarine to `A-82' and `Nemaguard'. Vegetative and fruiting responses of these trees will be discussed.
Cut flower Gerbera (Gerbera jamesonii Bolus) plants were grown in pots or ground benches under various photoperiods, levels of irradiance, and soil temperatures. Photoperiodic flowering response varied with the 3 cultivars; ‘Appelbloesem’ was not sensitive to photoperiod; ‘Oranje Nasau’ and ‘Fabiola’ were promoted by short day (SD). In pot-grown Gerbera, SD increased the number of flowers (inflorescences) per plant of ‘Oranje Nassau’ and ‘Fabiola’ in the summer-fall and fall-winter. Supplementary lighting with high-pressure sodium (HPS) lamps increased the fall-winter production of all 3 cultivars. Plants grown under 16 hr photoperiod by extending natural day length with incandescent light (INC) produced the least flowers per plant in both summer-fall and fall-winter. In bench-grown Gerbera, supplementary HPS increased the number of flowers during the fall-winter as compared to natural daylight (ND). Soil warming from 16°−20° to 23°C had no effect on productivity, but increased the peduncle length.
Peach trees (Prunus persica (L.) Batsch) dwarfed by phony disease responded to 2 summer applications of 264 ppm gibberellic acid (GA) by breaking the disease-induced rest period and resuming nearly normal twig growth. No twig growth was produced on untreated trees and no significant growth occurred on phony trees treated with combinations of cytokinins, sodium isoascorbate, calcium nitrate, urea, or citric acid.
Injecting CO2 gas into mist water (CO2 mist) promoted rooting of Ilex aquifolium L. ‘Silver Variegated Standard’ stem cuttings in spring propagation while inhibiting rooting in the fall. Supplementary lighting from high pressure sodium lamps (HPS) for 16 hr daily had similar effects as CO2 mist in the spring and inhibited root growth in fall propagation. There was a positive interaction between CO2 mist and HPS in spring propagation, suggesting that the promotive effects of these variables were due to enhanced photosynthesis.
Clematis × ‘Jackmanii’ (C. lanuginosa × C. viticella × C. × eriostemon) and Clematis × ‘Comtesse de Bouchard’ (cultivar of C. × ‘Jackmanii’) were evaluated for winter flowering with supplementary lighting treatments combining two photoperiods and two levels of irradiance during September to January. The dormancy of ‘Jackmanii’ was overcome by long (16 hr) days or by high (HPS) irradiance during natural photoperiods (8.5-12 hr); the dormancy of ‘Comtesse de Bouchard’ was overcome only by long days, irradiance having no effect. Terminal flower bud formation was affected similarly by supplementary lighting. The development of lateral flower buds of both cultivars was greatly enhanced by combining long photoperiods and high irradiance.
Nine pesticides (chlorothalonil, captan, benomyl, permethrin, methomyl, parathion, carbaryl, dicofol, and S) were sprayed on peach (Prunus persica L. Batsch ‘June Gold’) to determine pesticide-induced effects on leaf conductance (gl), transpiration (E), and net CO2 assimilation rate (A). Parathion was the only material to reduce A when applied <3 times. Net CO2 assimilation rate declined by 10% to 25% for parathion-, methomyl-, chlorothalonil-, benomyl-, and captan-treated trees after 3 applications; however, gl was reduced only for the parathion and chlorothalonil treatments. The pesticide-sensitivity of peach A appears to be much less than pecan and somewhat similar to apple. Chemical names used: 2,4,5,6-tetrachloro-l,3-benzenedi-carbonitrile (chlorothalonil); 3a,4,7,7a-tetrahydro-2-[(trichloromethyl)thiol]-lH-isoin-dole-l,3(2H)-dione (captan); methyl[l-](butylamino)carbonyl]-lH-benzimidazol-2-yl]carbamate (benomyl); (3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate (permethrin); methyl N-[[(methylam-ino)carbonyl]oxy]ethanimidothioate(methomyl); 0,0-diethyl 0-p-nitrophenylphospho-rothioate (parathion); 1-naphthalenyl methylcarbamate (carbaryl); and 4,4′-dichloro-α-trichloro-methylbenzhydrol (dicofol).