Fresh-cut peonies are one of few cut flowers that can be stored for weeks and still provide a marketable flower. Peonies are usually marketed by color: reds, pinks, whites, and corals. Several different cultivars may be included in each color depending on their country of origin and time during the harvest season. Previous work with peonies has shown that different cultivars of the same color may behave differently during postharvest handling, whether it is storage life, vase life, opening time, storage temperature, etc. One problem of long-term cold storage is diseases that may render flowers unmarketable. This study evaluated the effect of four storage disease prevention treatments on seven peony cultivars, two reds, two pinks, and three whites, stored at 1 °C. The four disease prevention treatments included a control, methyl jasmonate during storage, a pre-storage calcium chloride pulsing for 2 h at room temperature, and a pre-storage fungicide spray. Flowers were evaluated for disease incidence on leaves and flowers, and for flower bud openness after 4, 8, and 12 weeks of cold storage. Overall results support previous work that shows peony cultivars react differently to postharvest treatments. Two cultivars were greatly affected by the disease prevention treatments and three were moderately affected, while there were few treatment effects seen with the other two. The calcium chloride pulse produced the greatest disease incidence and resulted in the flowers being more opening, which is not desirable. There was often no difference in the control, methyl jasmonate, and fungicide treatments. It appears that pre-storage treatments may not be beneficial for some fresh-cut peony cultivars.
V.M. Russo and J.C. Díaz-Pérez
Heat stress can limit yield in pepper (Capsicum spp.), generally through flower and fruit abortion. A kaolin-based particle film, originally developed to protect fruit trees from insects, has been found to reduce temperatures in tissues of plants. A kaolin-based particle film was tested to determine if it could be used to improve yields of pepper in Oklahoma and Georgia. In Oklahoma, seedlings of a bell pepper, `Jupiter', and a nonpungent jalapeño, `Pace 103', were transplanted at three progressively warmer planting dates from mid-May to mid-July 2002 and 2003, that would ensure that inflorescences would be subject to high day and night temperatures and treated with the kaolin-based particle film. Applications were begun as the first flowers were set and continued through the settings of the first three flushes of flowers on a three-times a week schedule, or on an as needed basis, to determine if the kaolin-based particle film improved yield. In Georgia, the bell peppers `Camelot' and `Heritage VR' were transplanted on 24 Apr. 2003, and treated with the kaolin-based particle film. In addition to yield, physiological measurements and disease incidences were recorded in Georgia. In both locations treatment with water only served as controls. In Georgia, the kaolin-based particle film had no significant effect on net photosynthesis, stomatal conductance, leaf transpiration or leaf temperature, as measured at midday on clear days. In Oklahoma, planting bell pepper after 15 May is not recommended. Planting the nonpungent jalapeño after mid-June can reduce yields. The kaolin-based particle film did not affect yield at either location and is not recommended for use on peppers.
Jennifer Green, Derald A. Harp and Kevin L. Ong
Phytophthora diseases are economically important, requiring the use of chemical fungicides and, more recently, biological controls. Recent research suggests that composted bark products may lessen the impact of the disease, even in the absence of these chemicals. An experiment was conducted to compare chemical and biological fungicides to untreated pine bark compost. Impatiens wallerana plugs were transplanted from 288 trays into 1801 trays. All plants were planted into Berger BM-7, 35% composted bark mix (Berger Horticulture, Quebec, Canada). Media was prepared by premixing one of the five following fungicide treatments: 1) Control, 2) Banrot at 0.6 g/L, 3) Root Shield at 1.6 g/L, 4) Actino-Fe at 5.1 g/Ll, or 5) SoilGard at 1.6 g/L. Plants received no fertilizer. Three strains of Phytophthora were grown in 25 °C on clarified V8 media. Pathogenic inoculum was made by macerating the growth media and fungi in 100 ml H2O. Mixture was pulse-blended for 1 min, and an additional 200 mL dH2O was added. Inoculation was 5 ml per plant. Flats were kept on a misting bench, and misted twice daily for 15 min. The experiment was set up using a RBD repeated six times with three plants per rep. Plants were rated weekly for 5 weeks using a damage scale of 0 to 5, with 0 indicating no sign of disease and 5 being dead. Statistical analysis was conducted using a Chi-Square. Disease incidence between the biological, chemical, and composted bark treatments did not differ, with all treatments providing complete control. At least in this study, the use of composted pine bark media provided Phytophthora control equivalent to current chemical and biological fungicides.
Christopher S. Cramer, Neel Kamal and Narinder Singh
-Moghadam et al., 2011 ) and exhibited lower IYS disease incidence and severity. Seed of these breeding lines is available on request. Entries were evaluated with the additional intent of making selections within each entry of individual plants expressing fewer
Yun Kong, David Llewellyn, Katherine Schiestel, Martha Gay Scroggins, David Lubitz, Mary Ruth McDonald, Rene Van Acker, Ralph C. Martin, Youbin Zheng and Evan Elford
insects on each trap were counted weekly and used to determine cumulative totals at the end of crop production. Disease incidence was checked weekly, and the numbers of infected and dead plants due to disease were recorded in each plot. Weather parameter
E. Fava, D. Janik, C. Madramootoo and K.A. Stewart
Production of red bell peppers (Capsicum annuum L. cv. King Arthur) is relatively new to Quebec, and management techniques need to be further developed in terms of insect and disease control as well as fertigation techniques. The purpose of the experiment was to compare the fertigation of peppers using either the conventional method (weekly fertigation) or fertigation based on the readings of the SPAD 502 chlorophyll meter. The experiment compared the effects of these fertigation treatments, with respect to insects and diseases, on either a silver or black mulch. The study done in 1995, demonstrated that using the chlorophyll meter saved 28 kg N/ha compared to the weekly fertigated plants. However, this decrease did not affect the population of insects or the disease incidence on the plants. The main differences occurred between the black and silver mulch treatments for aphid populations. Plants on silver mulch had significantly lower numbers of aphids than the other treatments. Plants on black mulch also had low aphid population compared to plants grown on bare soil. The relationship between silver mulch and viruses or tarnished plant bug were not as apparent. However, the viral infections and tarnished plant bug populations on the plants tended to be lower than those on most of the black mulch treatments. Sunscald was not influenced by mulch or fertigation treatments. This may be partly attributed to the amount of leaf area. The number of fruit invaded by European corn borer was too low to draw any conclusions. Blossom end rot, sclerotinia, and bacterial spot were not present in the field in the 1995 season. The results from the 1996 season should further elucidate these results.
Kaori Ando and Rebecca Grumet
Fruit rot induced by Phytophthora capsici Leonian is an increasingly serious disease affecting pickling cucumber (Cucumis sativus L.) production in many parts of the United States. The absence of genetically resistant cultivars and rapid development of fungicide resistance makes it imperative to develop integrated disease management strategies. Cucumber fruit which come in direct contact with the soil-borne pathogen are usually located under the canopy where moist and warm conditions favor disease development. We sought to examine whether variations in plant architecture traits that influence canopy structure or fruit contact with the soil could make conditions less favorable for disease development. As an extreme test for whether an altered canopy could facilitate P. capsici control, we tested the effect of increased row spacing and trellis culture on disease occurrence in the pickling cucumber `Vlaspik'. Temperature under the canopy was lowest in trellis plots, intermediate in increased spacing plots, and highest in control plots. Disease occurrence in the trellis plots was significantly lower than in other treatments, indicating that preventing fruit contact with the soil reduced disease occurrence. The effect of currently available variation in plant architecture was tested using nearly-isogenic genotypes varying for indeterminate (De), determinate (de), standard leaf (LL), and little leaf (ll) traits. Plants with standard architecture had higher peak mid-day temperatures under the canopy and greater levels of P. capsici infection; however, levels of disease occurrence were high for all genotypes. Screening a collection of ≈150 diverse cucumber accessions identified to serve as a representative sample of the germplasm, revealed variation for an array of architectural traits including main stem length, internode length, leaf length and width, and number of branches; values for `Vlaspik' were in the middle of the distribution. Plant architectures that may allow for more open canopies, including reduced branching habit and compact growth, were tested for disease incidence. One of the compact lines (PI 308916), which had a tendency to hold young fruit off the ground, exhibited lower disease occurrence. The reduced disease occurrence was not due to genetic resistance, suggesting that architecture which allows less contact of fruit with the soil could be useful for P. capsici control for pickling cucumber.
Neel Kamal, Ashish Saxena, Robert L. Steiner and Christopher S. Cramer
down ( Wall and Corgan, 1994 ). In New Mexico, onion harvesting often coincides with rainfall and higher temperatures, conducive for development of black mold. Disease incidence can vary from 11% to 50% for short-day cultivars. No resistance to black
Babak Madani, Marisa Wall, Amin Mirshekari, Alagie Bah and Mahmud Tengku Muda Mohamed
before and after 3 weeks in storage. The results were expressed as percentage loss of initial weight. Apparent disease incidence was measured as the percentage of fruit showing disease symptoms out of the total number of fruit in each treatment. Apparent
Swee-Suak Ko, Woo-Nang Chang, Jaw-Fen Wang, Shin-Jiun Cherng and S. Shanmugasundaram
In the tropics, onion (Allium cepa L.) bulbs are usually stored in shelters under ambient conditions resulting in severe storage losses. This study was aimed at determining whether variation in bulb storability exists among short-day onion cultivars and whether the trait can be improved through conventional breeding. Twelve onion cultivars with different degrees of storability were selected from preliminary experiments. Bulbs of selected cultivars were grown and stored for 3 months under ambient conditions. Observations were made on disease incidence at harvest, percentage diseased bulbs, and storage disease incidence of bacterial soft rot [BR (Pseudomonas gladioli pv. alliicola Burkholder)], black mold [BM (Aspergillus niger Tiegh.)], and fusarium basal rot (Fusarium oxysporum Schlechtend.:Fr. f. sp. cepae) after 3 months of storage. Data on bulb characteristics such as bulb fresh weight (FW), dry matter (DM) content, total soluble solids (TSS), and pyruvic acid content were recorded at harvest. Mean storage losses of cultivars ranged from 21% to 99% over 3 years. Diseases were the major causes of storage losses, with BR and BM being the most predominant. Performance of most traits (including storage losses) was significantly influenced by year (Y), cultivar (G), and Y × G interaction. Heavy rainfall during bulb development in 1997 may have contributed to higher disease incidence at harvest, higher percentage of diseased bulbs during storage, and lower DM, and TSS of the cultivars. Cultivars with good storability, such as `Red Pinoy' and `Serrana', were less sensitive to stressful environments and high disease pressure. Incidence of storage diseases was significantly correlated with DM (r = -0.65 to -0.84) and TSS (r = -0.66 to -0.87), as well as incidence of BR (r = 0.57 to 0.94) in each year. Thus, they could be good indicators for evaluating storability. Cultivars with good storability tended to have small bulbs, as average bulb FW was positively correlated with incidence of storage diseases. Disease incidences on `Red Pinoy' and `Serrana', both in the field and in storage, were significantly lower than in the other cultivars, indicating they are tolerant to major storage diseases and that they could be used as donor parents for genetic improvement of onion storability.