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  • Author or Editor: Anthony D. Bratsch x
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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.

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An open-market window has been identified in Virginia for fall broccoli (Brassica oleracea var. italica). Vegetable producers using plasticulture systems can capitalize on this opportunity by growing broccoli as a second crop after summer vegetables. The objective of this project was to evaluate suitability of two broccoli cultivars, Everest and Gypsy, for the fall production of large single-heads (>6 inches in diameter) for the fresh market. Planting density and rate of nitrogen (N) fertilizer (25, 60, and 100 lb/acre N) effects on yield characteristics were evaluated in a plasticulture system during a 3-year study (2003–05) conducted with broccoli transplants at the Virginia Polytechnic Institute and State University Kentland Agricultural Research Farm near Blacksburg, VA. The percentage of large heads was cultivar, plant density, and N rate dependent. The midseason ‘Gypsy’ produced significantly higher total yield and head weight compared with the early-season ‘Everest’. The optimum density to maximize floret production per area was 12,500 plants/acre and a supplemental N rate of 100 lb/acre. This N rate significantly (P < 0.002) improved marketable yield, large head yield, and leaf N accumulation compared with the lower rates. The data indicate that the feasibility of growing fall broccoli using a plasticulture system depends on the number of large heads produced for the fresh market. This in turn will depend on the choice of cultivar, stand establishment, and the requirement for supplemental N fertilizer over the residual level available in the soil after the first crop.

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Thirty horseradish (Armoracia rusticana Gaertn., Mey., & Scherb.) cultivars from eight countries in Europe and North America and from advanced lines developed at the Univ. of Illinois were evaluated for horseradish peroxidase (HRP; electrical conductivity, donor: hydrogen peroxide oxido-reductase) activity. Nearly 86% of the activity was present in the taproot and lateral roots and 14% in the leaf petiole, but there was no activity in the leaf blade. The 30 cultivars were divided into three groups with high (eight cultivars), medium (13 cultivars), and low (nine cultivars) activities [11.58 to 16.97, 7.19 to 9.79, and 2.88 to 6.91 μmol·min-1·g-1 fresh weight (FW), respectively]. The cultivars with the highest activity were 819-A from the Illinois and 810-A from Switzerland with 16.97 and 16.67 μmol·min-1·g-1 FW, respectively. The cultivar with the lowest HRP activity was 244-A from the United States with 2.88 μmol·min-1·g-1 FW. Cultivar 819-A also had the highest protein concentration (4.92 mg·g-1 FW). When HRP activity was expressed per milligrams of protein, cultivar 167-A, also known as `Bohemian', had the highest activity and cultivar 244-A had the lowest (5.35 and 0.83 μmol·min-1·mg-1 protein, respectively).

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