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S. Alan Walters

Plastic mulches and rowcovers were evaluated in southern Illinois to determine their influence on watermelon mosaic virus (WMV) disease incidence and symptom severity in susceptible and tolerant summer squash (Cucurbita pepo). The use of either black or white mulch produced greater early and total marketable yields than no mulch (bare soil) on `Dividend' and `Multipik'. More fruit had WMV symptoms with no mulch than with mulch, regardless of cultivar. However, more severe WMV symptoms developed on the fruit of susceptible `Multipik' compared to tolerant `Dividend'. The use of plastic mulches provided greater and longer protection to `Dividend' compared to `Multipik'. However, `Dividend' fruit did eventually develop virus symptoms as disease incidence in production fields increased. Rowcovers reduced the number of alate aphids landing on plants which resulted in fewer plants with WMV symptoms and suppression of symptoms on squash plants regardless of mulch type. Rowcovers had a greater influence on reducing the incidence of WMV and the severity of symptoms on `Dividend' compared to `Elite'. Rowcovers did not reduce WMV on `Elite' by the end of the season and were more effective when used with white mulch compared to black mulch. Rowcovers suppressed the incidence and severity of WMV symptoms that developed on a virus tolerant squash cultivar for a greater length of time compared to a susceptible cultivar, which related to increased yields and fewer culls with virus symptoms on the tolerant cultivar.

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S. Alan Walters

Watermelon mosaic virus (WMV) is often the most limiting factor to cucumber (Cucumis sativus) production in the midwestern U.S. The influence of WMV on farm-gate revenues for nine slicing cucumber (or fresh market cucumber) cultivars was determined under high WMV disease incidence during 2000 and 2001. Over the two growing seasons, most cucumber cultivars produced excessive amounts of unmarketable WMV symptomatic fruit; however, no WMV symptoms were observed on any fruit produced by `Daytona' or `Indy'. `Thunder' produced some WMV symptomatic fruit but was significantly (P ≤ 0.05) less than that produced by all other cucumber cultivars, except for `Daytona' and `Indy.' Consistent high total farm gate-revenues over both years were produced by `Daytona' and `Indy' compared to other cucumber cultivars evaluated with the exception of `Thunder'. `Daytona,' `Indy,' and `Thunder' tended to produce greater early-season farm-gate revenues. However, late-season revenues of `Thunder' were reduced compared to `Daytona' and `Indy'. `Dasher II,' `General Lee,' `Greensleeves,' `Marketmore 76,' `Speedway,' and `Turbo' produced excessive amounts of unmarketable WMV symptomatic fruit which led to reduced farm-gate revenues. Cucumber cultivars without some level of resistance to WMV produced substantially less cumulative farm-gate revenues than those that had some level of resistance. `Daytona,' `Indy,' and `Thunder' were not the highest yielding cucumber cultivars evaluated in this study, but produced the highest farm-gate revenues due to higher levels of genetic resistance to WMV.

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S. Alan Walters

Garlic (Allium sativum) is a popular specialty vegetable sold at many local market venues. Recently, the demand for high-quality garlic has prompted grower interest in producing this crop for direct markets. A 2-year study was conducted at the Southern Illinois University Horticulture Research Center in Carbondale to evaluate eight currently recommended garlic cultivars on a silty loam soil, as well as compare garlic produced on bare soil during the winter and wheat (Triticum aestivum) straw mulch in the spring to black plastic. ‘Idaho Silverskin’ (softneck, silverskin type) and ‘Persian Star’ (hardneck, purple-stripe type) were the best cultivars of those evaluated for the lower midwestern United States based upon various yield and quality characteristics. ‘Idaho Silverskin’ and ‘Persian Star’ had 100% winter survival (regardless of production method), high bulb quality, low amounts of foliar disease, high marketable yields with low cull production (>96% of bulblets developed marketable bulbs), and low amounts of bulb rot (<7%). Black plastic provided greater winter protection for garlic (95% survival rate) compared with bare soil (85% survival rate). Greater marketable weights and bulb diameters (50% and 23% increase, respectively) resulted when garlic was grown in black plastic compared with the bare soil/wheat straw mulch treatment.

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S. Alan Walters

Mini triploid (seedless) watermelons (Citrullus lanatus) are a growing segment of the U.S. watermelon market due to their small, one-serving size. Although mini triploid watermelons were first released and commercially grown about 6 years ago, little information is available for optimum planting densities that are needed to achieve the greatest percentage of marketable fruit in the 3- to 8-lb range. In 2006 and 2007, the fruit grade distribution response to six plant densities (2489, 3111, 4149, 6223, 8297, and 12,446 plants/acre) of four mini watermelon cultivars (Betsy, Petite Treat, Valdoria, and Vanessa) was measured at the Southern Illinois University Horticulture Research Center in Carbondale. ‘SP-1’ was used as the in-row pollenizer at 25% of the total planting. Although all cultivars responded similarly to the plant densities evaluated, ‘Vanessa’ provided the greatest fruit number and weight per acre, and percentage of fruit in the mini grade, compared with the other cultivars. Marketable mini triploid watermelon yield dramatically increased with closer in-row spacings. At lower plant densities (wider in-row spacings), a greater proportion of icebox-sized fruit (>8 lb) was produced, and the amount of marketable, mini-sized fruit (3–8 lb) declined. The grade distribution of mini triploid watermelon numbers and weights were the greatest at the highest plant density evaluated [0.5 ft in-row spacing (12,446 plants/acre)], with about 80% of the total yield in the mini grade. The greatest net revenues were also obtained at this high density. This study indicated that it is critical for producers of mini triploid watermelons to recognize the dramatic impact that plant density has on marketable fruit yield (3–8 lb). Growers of mini triploid watermelons will see a drastic improvement in revenues with closer in-row spacings compared with the approximate 2 ft in-row spacings currently used (about 4000 plants/acre). The increased cost of higher plant densities are more than offset by the greater return on investment.

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S. Alan Walters

Cucurbit vegetable crops, such as watermelon (Citrullus lanatus), require insect pollination for fruit set, which is usually achieved by placing honey bee (Apismellifera) colonies in a field or relying upon natural bee populations. Pistillate (or female) watermelon flowers require multiple honey bee (or other bee) visitations after visiting staminate (or male) flowers for fruit set, and pollination is even more of a concern in triploid watermelon production since staminate flowers contain mostly nonviable pollen. Six honey bee visitation treatments, 1) no visitation control, 2) two visits, 3) four visits, 4) eight visits, 5) 16 visits, and 6) open-pollinated control, were evaluated to determine the effect of honey bee pollination on `Millionaire' triploid watermelon fruit set, yield, and quality utilizing `Crimson Sweet' at a 33% pollinizer frequency. No differences (P> 0.05) between honey bee pollination treatments were observed for `Millionaire' quality characters (hollow heart disorder or percent soluble solids). The lowest pistillate flower abortion rate (20%) and subsequently the greatest triploid watermelon yields (fruit numbers and weights per hectare) occurred with the openpollinated control compared to all other honey bee visitation treatments. Fruit abortion rates decreased linearly, while fruit numbers and weights per hectare increased linearly as number of honey bee visits to pistillate flowers increased from 0 (no visit control) to the open-pollinated control (≈24 visits). This study indicated that >16 honey bee visits are required to achieve maximum triploid watermelon fruit set and yields, which is twice the number of honey bee visits required by diploid watermelons to achieve similar results.

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S. Alan Walters

Honey bees (Apis mellifera L.) are important pollinators of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai]. Pistillate (or female) watermelon flowers require multiple honey bee or other wild bee visitations after visiting staminate (or male) flowers for fruit set, and pollination is even more of a concern in triploid watermelon production since staminate flowers contain mostly nonviable pollen. Six honey bee visitation treatments—1) no visitation control, 2) two visits, 3) four visits, 4) eight visits, 5) 16 visits, and 6) open-pollinated control—were evaluated to determine the effectiveness of honey bee pollination on `Millionaire' triploid watermelon fruit set, yield, and quality utilizing `Crimson Sweet' at a 33% pollenizer frequency. `Millionaire' quality characters (hollow heart disorder or percent soluble solids) did not differ (P > 0.05) between honey bee pollination treatments. The open-pollinated control provided the highest fruit set rate (80%) and the greatest triploid watermelon numbers and weights per plot compared to all other honey bee visitation treatments. Fruit set, and fruit numbers and weights per plot increased linearly as number of honey bee visits to pistillate flowers increased from 0 (no visit control) to the open-pollinated control (about 24 visits). This study indicated that between 16 and 24 honey bee visits are required to achieve maximum triploid watermelon fruit set and yields at a 33% pollenizer frequency, which is twice the number of honey bee visits required by seeded watermelons to achieve similar results. This is probably due to many honey bees visiting staminate triploid watermelon flowers (that are in close proximity) before visiting pistillate flowers thus providing mostly nonviable pollen that is useless for fruit set and development. Therefore, more honey bee visits to pistillate triploid watermelon flowers would be required to achieve maximum fruit set and subsequent development compared to seeded watermelons.

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S. Alan Walters* and Bradley H. Taylor

Most small pumpkin growers in Illinois have traditionally relied upon natural insect pollinators to achieve fruit set and development. Many growers fail to understand the importance of pollination and are not aware of the potential benefits of using honey bee colonies to improve pollination and subsequent fruit set of pumpkin. Therefore, a study was conducted over the 2000 and 2001 growing seasons to measure the effectiveness of honey bee colonies on jack-o-lantern pumpkin production. Yields (kg·ha-1) of several cultivars (e.g., `Appalachian' and `Howden') almost doubled when honey bee colonies were present during flowering. Pumpkin weights with the inclusion of honey bees averaged 31,547 kg·ha-1 compared to 22,353 kg·ha-1 for those without honey bees. However, the number of pumpkins per ha was not as drastically influenced by the addition of honey bees; total pumpkin fruits per ha averaged 1,896 with honey bees as compared to 1,704 without honey bees. These results indicate that there were sufficient natural pollinators to induce pumpkin fruit set under field conditions during the study, but fruit size can be significantly increased with the addition of a strong honey bee colony during flowering. Since pumpkins are generally sold on a weight basis, growers should realize greater revenues with the inclusion of honey bee colonies in pumpkin fields.

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S. Alan Walters and Todd C. Wehner

Root knot, caused by Meloidogyne spp. is the most important disease of cucumber (Cucumis sativus L.) in North Carolina, causing an average annual yield loss of 12 %. A greenhouse study was conducted 10 screen 924 cultigens (728 accessions, 136 cultivars and 36 breeding lines of C. sativus, and 24 accessions of C. metuliferus Naud.] for resistance to 3 species of root knot nematodes, M. incognita r. 3, M. arenaria r. 2 and M. hapla, Plants were grown from seed in 150-mm diameter clay pots. Two-week-old seedlings were inoculated with 5000 nematode eggs per plant, then evaluated for resistance 9 weeks later. All cultigens evaluated were resistant to M. hapla. Little resistance was found in the cultigens of C. sativus to M. incognita r. 3 and M. arenaria r. 2. Most of the cultigens evaluated were susceptible to both. `Southern Pickler' was resistant to both nematodes (1 % average galls). `Green Thumb and LJ 90430 were resistant to M. arenaria r. 2, Two check cultigens, `Sumter' and Wis. SMR 18, had an average of more than 50% galls. All C. metuliferus cultigens evaluated were resistant to all root knot nematodes tested. PI 482452 was most resistant (1 % average galls), and PI 482443 was least resistant (5% average galls) of the C. metuliferus cultigens tested.

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Joseph G. Masabni and S. Alan Walters

A field study was conducted in 2010 and 2011 to determine the suitability of Earth-Kind® production principles for home vegetable gardening. Earth-Kind® production encourages water and energy conservation, and reduction of fertilizer and pesticide use. Seven vegetable cultivars [Sweet Banana and bell pepper (Capsicum annuum); Celebrity and Juliet tomato (Solanum lycopersicum); Spacemaster cucumber (Cucumis sativus); Ichiban eggplant (Solanum melongena); Spineless Beauty zucchini (Cucurbita pepo)] were grown in mushroom compost (MC) or city compost (CC). Both composts were incorporated preplant into the soil with shredded wood mulch placed over them. In each year, nitrogen (N) fertilizer (15.5N–0P–0K from calcium nitrate) was applied preplant to CC plots to bring initial soil fertility levels similar to MC plots. No additional fertilizer was applied during the growing season. Drip irrigation was supplemented weekly. One application each of neem oil and pyrethrin (organic insecticides) and chlorothalonil (synthetic fungicide) was applied before harvest in 2010, but none was applied in 2011. Results indicated that Earth-Kind® technique could be effectively implemented in a home vegetable garden. MC is better suited for Earth-Kind® vegetable production than CC for some vegetables. Banana pepper, bell pepper, and zucchini had twice the yield in MC plots when compared with CC plots. No yield differences (P > 0.05) were observed between composts for tomato, eggplant, or cucumber. With proper irrigation and soil preparation practices such as addition of compost and mulch, Earth-Kind® vegetable gardening techniques can be used for selected vegetable crops without additional N fertilizer or pesticides. Furthermore, Earth-Kind® vegetable gardening can be successful as long as the home gardener understands that low yields may result from using this production method. However, often the home gardener is more concerned about producing vegetables using sustainable, environmentally friendly methods than maximizing yields.

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Dena C. Fiacchino and S. Alan Walters

During the 1999 and 2000 growing seasons in Illinois, studies were conducted to determine the influence of two pollinizers (`Crimson Sweet' and `Fiesta') and three pollinizer frequencies (11%, 20%, and 33%) on `Millionaire' seedless watermelon (Citrullus lanatus) quality and yields. More large-sized [>16 lb (7.2 kg)] `Millionaire' watermelons were produced when `Crimson Sweet' was used as the pollinizer compared to `Fiesta', which resulted in `Crimson Sweet' leading to greater marketable and total `Millionaire' yields. Pollinizers responded similarly over the pollinizer frequencies for `Millionaire' watermelon yields as no pollinizer by pollinizer frequency interaction was observed. The 20% and 33% pollinizer frequencies produced similar `Millionaire' yields per acre and both resulted in greater yields compared to the 11% pollinizer frequency. Soluble solids in `Millionaire' fruits were not influenced by pollinizer or pollinizer frequency. However, hollow heart disorder followed a quadratic response with respect to pollinizer frequency with the lowest amount of hollow heart observed at the 33% pollinizer frequency and greatest at the 11% pollinizer frequency. No significant interaction (P ≤ 0.05) was observed for pollinizer by pollinizer frequency for hollow heart disorder in `Millionaire'; although, more hollow heart disorder in `Millionaire' was observed when `Fiesta' was used as the pollinizer.