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  • Author or Editor: D. R. Hensel x
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Elderberry rust (Puccinia sambuci Schwein.) Arthur (=P. bolleyana) () disease is frequently found in commercial American elderberry (Sambucus nigra L. subsp. canadensis L.) plantings when an alternate host, Carex sp., is present. To evaluate potential infection periods of P. sambuci on elderberry plants, micrometeorological conditions were monitored. Rust symptoms were observed on elderberry on 5 Apr. 2016, and conditions favorable for possible infection were 9 to 18 °C, ≥3 hours of continuous leaf wetness, and ≥85% relative humidity. Studies were also conducted to ascertain whether P. sambuci with varying pustule numbers affects fruiting, berry puree quality, or vegetative growth. Fruit yield was reduced by 31% when potted ‘Bob Gordon’ elderberry averaged six rust pustules per plant compared with noninfected plants. In another experiment, field-grown ‘Wyldewood’ plants averaging 137 rust pustules/cane at harvest had 47% less fruit weight on canes than uninfected canes. Titratable acidity of fruit puree from plants was lower when plants had either 690 rust pustules/plant or 137/pustules/cane, but soluble solids and pH of puree were unaffected by P. sambuci infection. The effect of rust infection on vegetative growth of elderberry plants also varied with pustule numbers. With a low infection level (six pustules per plant), P. sambuci did not induce premature leaf loss on ‘Bob Gordon’ plants or adversely affect shoot dry weight at the end of the growing season. When P. sambuci infection on ‘Wyldewood’ plants was more severe (137 pustules/cane), greater leaf loss occurred on infected canes than on uninfected canes. At very high infection levels (690 pustules/plant), ‘Bob Gordon’ plant dry weight was reduced. Because of the potential for fruit yield loss on elderberry plants, control of P. sambuci at relatively low infection levels on this plant may be warranted. Strategies that eliminate or suppress the alternate host would likely reduce the P. sambuci inoculum and limit the potential for elderberry plant infection.

Free access

Abstract

Isobutylidene diurea (IBDU) and sulfur-coated urea (SCU) alone or in combinations with NH4NO3 were evaluated as N sources for potatoes (Solanum tuberosum L.) on 2 sandy soils. Nitrogen was applied either all preplant or in split application at 134 or 201 kg N/ha. Tuber yields were highest with NH4NO3 alone or with NH4NO3 combined with IBDU or SCU, and were lowest with 100% IBDU and SCU. Marketable yields obtained with NH4NO3 were 25% and 27% higher than with 100% IBDU and SCU, respectively. Marketable and total yields increased and tuber specific gravity decreased slightly with increased N. Split applications of N increased marketable and total yields at one location. Leaf N, Mg, and Ca concentrations were higher and K was lower with NH4NO3 alone or with NH4NO3 with IBDU or SCU than with IBDU and SCU. Nitrogen sources had no significant effect on soil total soluble salts, NO3-N, or NH4-N, 7 and 12 weeks after fertilization.

Open Access

Abstract

Large and small cabbage transplants of three cultivars were selected from plots produced from large, medium, small, and unsized seed. Physical measurements and yield data were obtained. Analysis of the means and the plant-to-plant variation showed the principal responses to be more readily accounted for by genetic than environmental factors. Plants of ‘King Cole’ were less variable than the other cultivars in height of heading.

Open Access