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- Author or Editor: Joel L. Shuman x
- HortScience x
Anthracnose fruit rot (AFR) and crown rot can cause severe economic losses on susceptible `Chandler' and `Camarosa' strawberry in Virginia: `Sweet Charlie' and `Bish' are moderately resistant to resistant. Actigard (acibenzolar-S-methyl), an inducer of systemic acquired resistance, has been effective at reducing black spot and speck on tomato, blue mold on tobacco, and fire blight on apple. The objective of this study was to determine if Actigard, when spray-applied to field-grown strawberry, can reduce AFR better than or equal to several registered fungicides. Four varieties (VAR) (Chandler, Camarosa, Sweet Charlie, and Bish) were treated with four fungicides (FUNG) (water control, azoxystrobin, chlorothalonil, and actigard). Experimental design was a split plot with FUNG as the main plot and VAR as the split plot with four replicates. Standard annual hill system practices were used throughout. Plots were inoculated three times throughout the harvest season with a conidia: water solution of 1 × 106 conidia per mL. Plots were treated with FUNG on a 14-day schedule from bloom to end of season. Plots were visually assessed for anthracnose and fruit were harvested 2× weekly and weighed into four categories: marketable, cull, fruit with anthracnose, and fruit with other diseases. Environmental conditions were conducive for anthracnose development: extended periods of rain and high relative humidity. Plots treated with water control had more AFR, other fruit rots, and higher overall disease ratings than those treated with a compound. Plots treated with actigard had the same level of AFR as did those treated with azoxystrobin. `Chandler' and `Camarosa' had considerably more AFR than `Sweet Charlie' and `Bish' had the least amount over all FUNG.
Production of pickling cucumber (Cucumis sativus L.) requires a significant expenditure of labor and money. Those resources could be better managed if both yield and harvest date could be predicted for a given planting date and production area. The objective of this experiment was to develop a model to simulate growth and yield of pickling cucumbers under field conditions in North Carolina. Detailed measurements of leaf area, branching habit, flowering, fruiting, and dry weight distribution were obtained for the cultigens `Calypso', M 21, `Wis. SMR 18', and WI 2757 for 10 planting dates. Light interception, air temperature, and rainfall were also recorded. There were differences among cultigens and planting dates for time needed to reach certain growth stages. Number of days to reach a given stage generally decreased with later planting dates. Addition of nodes over time to the main stem was linear and the interaction of planting date by cultigen was significant. Number of staminate and pistillate flowers was affected by both cultigen and planting date.
Drought and heat stress have been extensively studied in plants, but little is known about how the combination of drought and heat impact their physiology and metabolism. The metabolite profile of Arabidopsis subjected to heat, drought, and the combination of heat and drought were analyzed by gas-chromatography-mass spectrometry (GC-MS). Fatty acid retention time standards and the internal standard (IS) ribitol (adonitol) were added to each leaf sample and the polar phase was extracted, methoximated, and derivatized (trimethylsilylated) prior to analysis by GC-MS (Trace DSQ with Combi-PAL autosampler). Compounds were identified based upon retention time (relative to fatty acid standards) and comparison with reference spectra in our custom mass spectral library. Semi-quantitation of compound peak area was done relative to the internal standard. Plants subjected to both heat and drought stress accumulated sucrose and other sugars/sugar alchohols such as maltose, gulose, mannitol. The amino acid proline (Pro) was found in drought-stressed plants, but not found in drought- and heat-stressed plants. Proline has been reported to function as an osmoprotectant in cold-, salt-, and drought-stressed plants, but could be toxic to drought- and heat-stressed plants. We found that growth of heat-stressed Arabidopsis seedlings is inhibited by Pro, but not in drought- and heat-stressed seedlings. These results also indicate that sucrose replaces proline as the major osmoprotectant in heat- and drought-stressed plants. Plants subjected to combined heat and drought also exhibited enhanced respiration, suppressed photosynthesis, and distinct transcriptome expression.