Salvadore J. Locascio

Blossom-End Rot: A Calcium Deficiency

Abstract Blossom-end rot (BER) is a common physiological disorder that occurs on the fruit of tomato (Lycopersicon esculentumMill.), pepper (Capsicum annuumL.), eggplant (Solanum melongenaL.), and watermelon [Citrullus lanatus(Thunb.) Matsun & Nakai]. BER may occur in all the tomato-producing areas of the world and has been shown to create losses up to 50%. BER is related to many factors including: high salinity, high magnesium (Mg), ammonium (NH4), and/or potassium (K) concentration, inadequate xylem tissue development, accelerated growth rate, unfavorable moisture relationships (high, low, or fluctuating), low soluble soil calcium (Ca), high temperature, and high and low transpiration, but the underlying cause of this disorder is an inadequate amount of Ca in the blossom-end of the fruit. Although it is widely accepted that a local Ca deficiency plays an important role in the induction of BER, there are also some claims that Ca deficiency is not the cause of BER as a critical level of Ca for BER induction has not been found. To prevent BER from occurring, an understanding of Ca in the soil, uptake and translocation of Ca, and the factors affecting these processes, is necessary.

Season-Long Interference of Yellow Nutsedge (Cyperus esculentus) with Polyethylene-Mulched Bell Pepper (Capsicum annuum)1

Yellow nutsedge, a weed commonly present in Florida vegetable fields, may substantially reduce crop yields when not controlled. Soil fumigation with methyl bromide effectively controls nutsedges, but methyl bromide is being phased out of production and use in the United States. Therefore, nutsedge management in bell pepper is a cause for concern. An experiment was conducted during four seasons (spring and fall of 1999 and 2000) to determine the tolerance of bell pepper grown at two in-row spacings (23 and 31 cm) to interference resulting from planted yellow nutsedge tuber densities (0 to 120 tubers/m2). Relative to yields with no nutsedge, pepper fruit yields in each season were reduced 10% with fewer than 5 planted tubers/m2. Yield losses increased more rapidly with an increase in initial nutsedge density from 0 to 30 than from 30 to 120 tubers/m2. With 30 nutsedge tubers/m2, large fruit yield was reduced 54 to 74% compared to that with no nutsedge. Nutsedge shoots overtopped the pepper plants as early as 6 wk after treatment when, with 15 planted tubers/m2, nutsedge interference reduced pepper plant biomass by 10 to 47%. In the absence of methyl bromide, weed control strategies with high efficacy against yellow nutsedge will be needed for bell pepper production. Nomenclature: Methyl bromide; yellow nutsedge, Cyperus esculentus L. #3 CYPES; bell pepper, Capsicum annuum L. ‘X3R Camelot’. Additional index words: Weed interference, yellow nutsedge competition, yield loss. Abbreviations: No., number; WAT, weeks after treatment.

Phytotoxic Effects of Glyphosate on Pepper (Capsicum annuum)1

Abstract: Glyphosate was applied to pepper as single or sequential applications to assess the consequences of drift or other accidental exposures. Foliar injury increased and plant vigor declined with increased rates of glyphosate and were exacerbated by a second application. Single applications at flowering (stage 1) were more damaging than single applications after fruit set (stage 2). Decline in marketable yield with increased glyphosate rate was greater with stage 1 applications, except in spring 1987 when marketable yields with single applications of glyphosate at stage 1 or stage 2 were statistically similar. Sequential applications resulted in the lowest marketable yields. Total yields declined with increased glyphosate rate and decline was more pronounced with sequential applications than with single applications. Total yield was affected to a greater extent when glyphosate was applied at stage 1 than at stage 2. Yield was more sensitive to two successive exposures than to single applications. Mean fruit weight was reduced by glyphosate in two of the four experiments. Nomenclature: Glyphosate; pepper, Capsicum annuum L. Additional index words: Simulated drift, herbicide injury. Abbreviations: DAT, days after treatment; WAT, weeks after treatment.

Evaluation of a computer model to simulate water table response to subirrigation

(3) and Salvadore Jose Locascio(4) Abstract - The objective of this work was to evaluate the water flow computer model, WATABLE, using experimental field observations on water table management plots from a site located near Hastings, FL, USA. The experimental field had scale drainage systems with provisions for subirrigation with buried microirrigation and conventional seepage irrigation systems. Potato (Solanum tuberosum L.) growing seasons from years 1996 and 1997 were used to simulate the hydrology of the area. Water table levels, precipitation, irrigation and runoff volumes were continuously monitored. The model simulated the water movement from a buried microirrigation line source and the response of the water table to irrigation, precipitation, evapotranspiration, and deep percolation. The model was calibrated and verified by comparing simulated results with experimental field observations. The model performed very well in simulating seasonal runoff, irrigation volumes, and water table levels during crop growth. The two-dimensional model can be used to investigate different irrigation strategies involving water table management control. Applications of the model include optimization of the water table depth for each growth stage, and duration, frequency, and rate of irrigation.