Christine Taylor Stephens
Renee DeVries-Paterson, Christine Stephens and Thomas Evans
Commercial asparagus (Asparagus officinalis L.) is currently planted from seed but there is a growing interest in the use of tissue culture clones. The worldwide occurrence of asparagus virus I (AV-I) and asparagus virus II (AV-II) in asparagus production areas has led to an investigation of the effect of these viruses singly and in combination on the propagation of asparagus via tissue culture. Bud explants from field-grown, virus-infected asparagus plants were cultured in-vitro to induce shoots and roots. Explants derived from singly or doubly-infected plants were slow to develop roots and often died in culture. The four virus groups were ranked for the explants' capacity to produce roots and shoots: virus-free > AV-II > AV-I> AV-I and AV-II. Plants derived from explants of AV-II-infected plants exhibited a mild weight reduction after three months in the greenhouse. Greater reductions were associated with AV-I and double infections when compared to healthy controls.
Tracy L. Wacker, Gene R. Safir and Christine T. Stephens
Asparagus (Asparagus officinalis L.) seedlings inoculated with the sicular-arbuscular mycorrhizal (VAM) fungus Glomus fasciculatum (Thaxt. sensu Gerd.) Gerd. & Trappe (GF) d Fusarium oxysporum (Schlect.) Snyd. & Hans. (FO) were grown under field and greenhouse conditions. In the fi, shoot volumes of GF-inoculated plants were greater than nonGF plants from the 3rd through the 13th month of growth. By the 14th month, GF-inoculated plants grown in high-P soils had significantly lower disease ratings than nonGF plants grown in low-P soils, and rhizosphere populations of FO were lowest in high-P soils, regardless of VAM status. In greenhouse studies, FO inoculation of VAM-infected asparagus plants reduced GF root colonization levels under well-watered (0 MPa), but not under water stress, conditions (- 1.5 MPa). Well-watered plants inoculated with both FO and GF were less diseased and sustained lower rhizosphere populations of FO than plants inoculated with FO alone. The differences in FO populations and disease ratings in these studies were apparently unrelated to final plant tissue P levels.
Rachel A. Kreis, Holly W. Lange, Stephen Reiners and Christine D. Smart
Twelve commercial cauliflower (Brassica oleracea var. botrytis) varieties were evaluated for horticultural traits and susceptibility to alternaria leaf spot (Alternaria brassicicola) at the New York State Agricultural Experiment Station in Geneva, NY, in 2014 and 2015. Data including total yield, curd weight, curd width, plant height, days to maturity, and length of harvest were collected for each variety. A duplicate trial was planted in each year and inoculated with A. brassicicola, the causal agent of alternaria leaf spot, and the percentage of disease was assessed for each commercial cauliflower variety. Most of the commercial varieties were similar in susceptibility to disease and yield. ‘Artica’ and ‘Apex’ were ranked among the highest yielding varieties each year of the trial. The varieties ‘Graffiti’ and ‘Violet Queen’, both of which produce purple curds, had significantly less alternaria leaf spot compared with other varieties. Differences were seen between the 2 years of the trial in performance of individual varieties as influenced by temperatures during the growing season. This study demonstrates that some cauliflower varieties perform better than others under New York State growing conditions.
Amara R. Dunn, Lindsay E. Wyatt, Michael Mazourek, Stephen Reiners and Christine D. Smart
In 2011, total marketable yield, fruit size, and number of lobes; fruit discoloration due to silvering; and plant structure were compared among eight commercial green bell pepper (Capsicum annuum) varieties and four breeding lines at three field sites in central New York. Tolerance to phytophthora blight (Phytophthora capsici) was also assessed at one of these sites. No wilting or plant death due to phytophthora blight was observed on the four breeding lines. ‘Paladin’, ‘Intruder’, and ‘Aristotle’ had the highest levels of tolerance to phytophthora blight, among the commercial varieties and maintained their yields in the presence of disease. In the absence of phytophthora blight, yields from these three varieties were comparable to susceptible varieties, but fruit tended to be smaller, and incidence of silvering was high in ‘Paladin’ and ‘Intruder’. Less silvering was observed on ‘Aristotle’ fruit. Total marketable yields from the breeding lines and percent of fruit with four lobes was comparable to the commercial varieties, and some breeding lines also had a low incidence of silvering, but fruit were smaller and set later in the season. Overall, this study suggests that ‘Paladin’, ‘Intruder’, and ‘Aristotle’ will yield well in fields with a history of severe phytophthora blight, but new large-fruited varieties with low incidence of silvering and good tolerance to phytophthora blight are needed.
Lindsay E. Wyatt, Amara R. Dunn, Matthew Falise, Stephen Reiners, Molly Jahn, Christine D. Smart and Michael Mazourek
Phytophthora capsici is an oomycete pathogen that causes disease on bell pepper (Capsicum annuum) and many other vegetable crops globally. Newly developed bell pepper inbred lines have been shown to be resistant to P. capsici and have been previously evaluated for green harvest yield. Nine P. capsici-resistant inbred lines and three commercial cultivars were evaluated for red harvest yield and fruit characteristics at three sites and disease resistance was evaluated through field inoculation studies. Three of the P. capsici-resistant lines were further evaluated as hybrid parents by measuring hybrid yield and disease resistance. P. capsici-resistant lines had excellent disease resistance and provided high levels of resistance to F1 hybrids. Inbred lines had comparable yields to the commercial cultivars, but fruit were smaller in size and weight. These lines are suitable for use as inbred lines for markets where small fruit size is acceptable and have potential for use as hybrid parents.