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  • Author or Editor: M.M. Bates. x
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Mixtures of (2-chloroethyl)phosphonic acid (ethephon) plus gibberellic acid (GA3) were applied to ‘Edisto-47’ muskmelon (Cucumis melo L.) plants at the 3–4 true leaf stage for 3 growing seasons. Ethephon at 240 mg/liter + GA3 at 100 mg/liter consistently increased the marketable yield of melons over the control. However, at 480 mg/liter ethephon, increased GA3 concentration from 50 to 150 mg/liter decreased yields. Average fruit weight and lengthdiameter ratios were increased by all ethephon + GA3 combinations, compared to the untreated control. Increased soluble solids and sweetness by 240 mg/liter ethephon + 100 or 150 mg/liter GA3 combinations were associated with increased fruit weight.

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Commercial N fertilizer formulations, ammonium nitrate, calcium nitrate, sodium nitrate, potassium nitrates (15-0-14 and 13-0-44) applied at 84 and 168 kg N/ha in 3 or 5 split applications did not affect total marketable yield of dry onion. Application frequencies causing an increase in total amount of N applied during the spring months (Feb.-Apr.) increased marketable yield by 5 MT/ha. Bulb decay was the highest when ammonium nitrate was applied, whereas the least number of decayed bulbs resulted from sodium nitrate applications. Plants grown with potassium nitrate (13-0-44) were most susceptible to cold injury. Ammonium nitrate and sodium nitrate applications produced the highest percentage of onions that bolted. The lowest percentage of plants showing bolting incidence resulted from calcium nitrate applications. Bolting of onions was closely associated with rapid growth and increased onion size. However, cold injury and bulb decay were not influenced by these growth factors.

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Various applications of N fertilizer formulations to bell pepper plots were made to affect soil nitrate-N concentrations from 5 to 30 ppm throughout the growing season. Number and weight of marketable grades for the 1st and 3rd harvests were improved by increasing soil N from 5 to 30 ppm. In the final (4th) harvest, marketable yield was highest for applications maintaining soil N of 25 ppm. Earliness was enhanced by N sources with Ca(NO3)2 producing the earliest yield followed by NaNO3 and NH4NO3. Total marketable yield produced by Ca(NO3)2 or NaKNO3 was 3 t/ha higher than by NH4NO3 applications. High marketable quality was maintained with Ca(NO3)2 and NaNO3 treatments. The highest blossom-end rot (BER) incidence was associated with NH4NO3 applications. But the N source effect on BER was strongly influenced by soil nitrate levels. At 10-20 ppm soil N, leaf Ca decreased during the 8 to 12 week period, but at higher soil N, leaf Ca remained unchanged, indicating a constant Ca uptake during the critical growth period.

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Abstract

Ripening of pimiento and paprika peppers (Capsicum annuum L.), tested at 2 locations, was accelerated by (2-choroethyl)phosphonic acid (ethephon) when applied close to normal fruit maturity. Potential chemical ripeners of Buckman Laboratories, BL-2142 (Poly[oxyethylene(dimethylimino)-ethylene(dimethylimino)ethylene dichloride]) and BL-2143 (Poly[hydroxyethylene(dimethylimino)-ethylene(dimethylimino)methylene dichloride]) slightly enhanced ripening of pimiento, but had little or no effect on paprika. Ethephon (1500 to 3000 ppm) applications induced defoliation and fruit abscission in pimiento and paprika, especially at later stages of fruit development. Extractable red color of dehydrated paprika was improved by ethephon and BL-2143 at 1000 mg/liter.

Open Access

The susceptibility of fraser fir (Abies fraseri), canaan fir (A. balsamea var. phanerolepis), and nordmann fir (A. nordmanniana) to phytophthora root rot (PRR) incited by Phytophthora cactorum or P. drechsleri was assessed in two experiments in central Pennsylvania. In an 8-week greenhouse study, seedlings and transplants growing in soilless substrate were inoculated with Phytophthora in flooded and non-flooded settings. In an 8-week outdoor study conducted in raised planting boxes filled with soil, transplants were inoculated with Phytophthora species in well-drained and poorly drained soil. Based on foliar disease ratings, mortality rates, and dry shoot and root weights, differences in susceptibility to P. cactorum and P. drechsleri existed between these true fir (Abies) species. Fraser fir was very susceptible to P. cactorum and P. drechsleri. Canaan fir had strong resistance to P. cactorum and P. drechsleri in well-drained settings but was susceptible in poorly drained settings. Nordmann fir had very strong resistance to P. cactorum and P. drechsleri in both well-drained and poorly drained settings.

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The most serious disease problem in fraser fir (Abies fraseri) Christmas tree production is phytophthora root rot (PRR). The efficacies of six fungicide treatments in preventing PRR incited by Phytophthora cactorum and P. drechsleri in 2-year-old fraser fir seedlings were evaluated in 2010 and 2011 in central Pennsylvania. The study examined five fungicide drench treatments [dimethomorph, fosetyl-aluminum (fosetyl-Al), hydrogen dioxide, mefenoxam, propamocarb hydrochloride] and one soil spray treatment (mefenoxam) in raised planting boxes. Dimethomorph applied on 14-day intervals prevented foliar disease symptoms and mortality in fraser fir seedlings exposed to either P. cactorum or P. drechsleri. One-time application of fosetyl-Al or mefenoxam were effective at times in preventing foliar disease symptoms and mortality in fraser fir seedlings exposed to P. drechsleri but were not as effective against P. cactorum.

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Horticulture students often lack practical experience integrating information from diverse sources to solve complex real-life problems. Capstone courses seek to remedy this by giving students an opportunity to demonstrate a range of workplace skills such as teamwork, effective communication, and critical thinking. Sponsored competitions provide educators with an active-learning framework into which the goals of a capstone course can be developed. The Greenhouse of the Future competition allowed undergraduate students to conceptualize, develop, and prototype innovative greenhouse designs in a national competition venue. This article explains the guidelines of the Greenhouse of the Future competition and discusses how the competition was integrated into the capstone course Greenhouse Management.

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Shoot and root water potentials were determined for bare-root Norway maple (Acer platanoides L.) and washington hawthorn (Crataegus phaenopyrum Med.) seedlings subjected to shoot and root exposure treatments for six cold storage durations. Shoot and root water potentials for all exposure treatments and both species decreased with increased time in storage, and the greatest degree of water stress occurred during the first six weeks of storage. Maple shoot and root water potentials for the exposed shoot treatment were the same as the whole plant covered treatment. In contrast, hawthorn shoot and root water potentials for the exposed shoot treatment were the same as values for the roots exposed treatment. Based on these data, we conclude that desiccation sensitive species such as washington hawthorn require root and shoot protection to minimize water loss.

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Two-year-old Washington hawthorn (Crataegus phaenopyrum Med.) and Norway maple (Acer platanoides L.) seedlings were subjected to varying cold storage durations and four storage treatments: whole plant covered in polyethylene bags, shoots exposed, roots exposed, and whole plant exposed. After storage, half the seedlings were immediately plant and half received a 12-hour desiccation treatment before transplanting. Root growth potential (RGP), time to budbreak, and marketability were measured. With the root covered treatments, Norway maple RGP increased while Washington hawthorn RGP decreased with increased cold storage duration. RGP for both species remained low throughout storage for treatments exposing roots. The 12-hour desiccation treatment reduced RGP for both species with hawthorn being more affected than maple. Days to budbreak for both species decreased with increased storage time for whole plant covered treatments but increased for both species when stored with exposed roots. Maple marketability for root covered treatments was high for most storage durations. Hawthorn marketability was generally low except for the whole plant covered treatment during the first 6 weeks of storage. For the respective storage durations, hawthorn RGP, time to budbreak and marketability values for the shoots exposed treatment were similar to the root exposed treatments. In contrast, values for the shoots exposed treatment were similar to the whole plant covered treatment for maple. There was a high positive correlation between RGP and marketability for both species.

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