Please handle this volume with care. The University of Connecticut Libraries, Storrs 3 11S3 Dimfl77=l E The Connecticut Agricultural Experiment Station, New Haven Pumpkin Trials 1992-1993 BY DAVID E. HILL C-dmM Bulletin 919 April 1994 SUMMARY In 1992-93, a total of 14 cultivars of large to small pumpkins were grown at Windsor in a sandy terrace soil and at Mt. Carmel in a loamy upland soil. In 1992, average yield at Mt. Carmel was 12.4 T/A compared to 7.0 T/A at Windsor. The low yield, especially at Windsor, was due to an infection of Phytophthora which rotted 24-97% of fruit in each cultivar at both sites. In 1993, the average yield at Windsor was 26.1 T/A compared to 13.6 T/A at Mt. Carmel. The lower yield at Mt. Carmel was due to persistent drought from June to August which caused the fruit to mature early while they were still small. Despite poor yield of most cultivars in 1992, yield of Cormecticut Field exceeded 20.0 T/A at both sites. The yield of Howden exceeded 19.0 T/A at Mt. Carmel. In 1993, the heavy yield of Big Autumn (58.0 T/A) was attributed to large average weight (16.0 lb) and prolific fruit production (7,200/ A). Yield of Pro Gold 500 and Connecticut Field also exceeded 30 T/A at Windsor. Yield of miniature pumpkins, Baby Bear and Oz, exceeded 12.0 T/A at Windsor. At Mt. Carmel, yield of Big Autumn, JSS 9032, and Pro Gold 500 exceeded 18.0 T/A. In 1992, post-harvest loss of unprotected fruit, due to frost damage in October, was least for Connecticut Field and Howden. In 1993, Big Autumn and Pro Gold 500 had the least frost damage of all cultivars. Among all cultivars. Big Autumn, Howden, JSS 9032, and Pro Gold 500 provided excellent yield and quality of fruit. High yield and quality were dependent upon weather and adequate control of Phytophthora, black rot, powdery mildew, cucumber beetles, and vine borers. ^^^mi^, bi\ {\SJ'] j^ T^he Connecticut Agricultural Experiment Station , '^j\^^-C^;^>'^c,^ founded in 1875, is the first experiment station in America. It is chartered ^Hx . nO^^ by the General Assembly to make scientific inquiries and experiments regarding plants and their pests, insects, soil and water, and to perform analyses for State agencies. The laboratories of the Station are in New Haven and Windsor; its Lockwood Farm is in Hamden. Single copies of bulletins are available free upon request to Pub- lications; Box 1 106; New Haven, Connecticut 06504. ISSN 0097-0905 i [,s: n 1 r Pumpkin Trials 1992-1993 BY DAVID E. HILL Pumpkins are members of the genus Cucurbita whose orange fruit is highly prized for fall decoration and as pie and bread ingredients. Most pumpkins belong to the species C. pepo, C. moschata, and C. maxima. C. pepo was cul- tivated by pre-Columbian natives from the Mexico City area northward to the southwestern United States (Yamaguchi 1983). This species is most tolerant to cold weather, hence its northward spread into the Midwest and East. It was reported that pumpkins were originally grown for their edible seeds (Splittstoesser 1979). The fruit is also edible and contains high amounts of Beta-carotene. Present outlook The marketing of pxmipkins for Halloween decoration and pie filling has increased substantially in the last decade. Many growers of fruit and vegetables who tailor their pro- duction for pick-your-own clientele now include a pumpkin patch in their plans. In 1989, the Connecticut Agricultural Marketing Directory listed 29 farmers who grew pick-your- own pumpkins. Another 32 growers listed pumpkins as a major item in their fall sales. Virtually all roadside stands that remain open through October have pumpkins to sell. There are also several growers who supply retail outlets. Although the precise area devoted to pumpkins is unknown, the Connecticut Department of Agriculture estimated that 800-1000 acres were grown in Cormecticut in 1993. To maximize production of pumpkins and to increase sales, growers must choose cultivars that are uniform in color and shape. Many open pollinated cultivars are inconsistent in these qualities. Because decorative pumpkins are mostly selected by eye appeal, a substantial number of pumpkins with defects are left in the field. Breeders have developed many new hybrid cultivars that are more uniform in color and shape and also resist mildew and rot. A new breeding objective is to develop cultivars whose seeds are hulless and readily edible. In this bulletin, I shall report yield and quality of 14 cul- tivars, ranging in size from large to miniature. I shall also re- port on post-harvest losses of pumpkins during 4 weeks of unprotected storage. Strategies to maximize yield will also be discussed. METHODS AND MATERIALS Soils Pumpkin trials were conducted at the Valley Laboratory, Windsor on Merrimac sandy loam, a well drained, sandy terrace soil with somewhat limited moisture holding capacity and at Lockwood Farm, Mt. Carmel on Watchaug loam (1992), a moderately well drained loamy upland soil, and on Cheshire fme sandy loam (1993), both with moderate mois- ture holding capacity. Cultivars Seeds were obtained from several domestic suppliers. A total of 14 cultivars of pumpkins were grown during the 2-year trial (Table 1). Table 1 . Pumpkin cultivars grown at Windsor and Mt. Carmel during 1992-1993. Cultivar Characteristics* 1992 1993 Aspen X Autumn Gold PYG X Baby Bear SH X Big Autumn SB, PYG X Connecticut Field X X Ghost Rider X X Howden X JSS 9032 X Lumina WHITE X New England Pie X Oz SB, PYG X X Pro Gold 500 X Spirit X Wizard SB X X *SB = Semi-bush; PYG = Precocious yellow gene; SH = Semi-huUess seed Connecticut Agricultural Experiment Station Bulletin 919 T 1 1 r 1 1 r 1 1 1 r 1 1 1 1 1 1 1 1 1 1 1 I r WINDSOR L iT MT. CARMEL 2^ m^ r I I 1 1 I 1 I I I I 1 1 1 1 \ 1 1 L JJASO JJASO JJASO JJASO 1992 1993 1992 1993 Figure 1. Departure from normal rainfall (0) during the growing seasons 1992-1993 at Mt. Carmel and Windsor. Semi-bush (SB) cultivars have shorter vines and require less planting space. Cultivars with precocious yellow genes (PYG) are yellow to orange throughout their growth instead of green changing to yellow or orange as they mature. Culti- vars with semi-hulless seed (SH) can be readily used for toasted snacks. Culture Seeds were sown June 2-5 in groups of 5-7 seeds. The groups were spaced 5 feet apart within rows that were 8 feet apart (1090 planting groups/A). After germination, the plants were thinned to 3 plants/group (1992) and 5 plants/group (1993). At the denser population in 1993, the plants, after thinning, were at least 10 inches apart within each group. In 1992, the plants, after thinning, were 6 inches apart. At each location, there was one row for each cultivar. In 1992, irri- gation was not necessary at either site because rainfall was sufficient from June through September. In 1993, a dry year, two irrigations were required at both sites. Fertilization Before planting, 3-foot wide planting swaths of soil were fertilized at a rate of 900 lb/A 10-10-10 (90 lb N/A). After 4 weeks, when the plants began to form vines, the un- fertilized 5-foot swaths between the rows were fertilized at a rate of 500 lb/A 10-10-10 (50 lb N/A) and rototilled into the soil. Soil pH was about 6.5 at each site; lime was not added. Disease control A pre-plant application of Ridomil 2E (2 qt/A) was disked into the soil to a depth of 2 inches to control Phyto- phthora crown and fiiiit rot. Black rot and powdery mildew were confrolled with alternate weekly applications of Bravo 500 (3 pt/A) and Ridomil-Bravo 81 W (2 lb/A) from mid- June to mid-August. Benlate DF (0.5 lb/A and Karathane (0.5 lb/A) were also applied alternately each week from late- June through August to confrol powdery mildew. Insect control Asana XL (9.6 oz/A) was applied weekly from mid- June through mid-July to confrol vine borers and cucumber beetles. Weed control Weeds were confrolled by cultivation. Weeds germinat- ing in the 4-week period following planting were rototilled under as the late fertilizer application was incorporated into the soil. Within 3 weeks, the vines completely covered the spaces between the rows and suppressed ftirther weed growth. Harvest All pumpkins were harvested from September 20 to October 10. The pumpkins were weighed individually and graded for color, shape, thickness of handle, and presence of surface blemishes. All pumpkins remained unprotected at the edge of the field and were re-graded October 29-30 to deter- mine post-harvest loss from rotting or frost damage. Rainfall and temperature Rainfall disfribution throughout the pumpkin growing season, June through October (1992-1993), is shown in Fig- ure 1. Each bar represents the departure from the mean monthly rainfall for Hartford and Mt. Carmel reported by the Pumpkin Trials 1992-1993 National Weather Service. In 1992, total rainfall from June through October was 21.1 inches at Windsor and 25.4 inches at Mt. Carmel compared to means of 15.7 inches and 16.2 mches respectively at each site. In 1992, the above-average rainfall from June to August at Windsor and June to Septem- ber at Mt. Carmel, provided adequate moisture for the growing crop, but caused an extensive infection of Phytoph- thora at both sites. Pre-harvest and post-harvest loss of fruit were extensive despite attempts to confrol the disease. Addi- tional post-harvest loss of fruit by frost damage occurred on nights when the temperature fell as low as 28F. In 1993, total rainfall during the growing season for pumpkins was 17.0 inches at Windsor and 15.5 inches at Mt. Carmel, compared to means of 15.7 inches and 16.2 inches respectively at each site (Figure 1). At Mt. Carmel, below- average rainfall from June to August severely stunted the crop and caused the pumpkins to mature earlier than normal. At Windsor, several local thunderstorms in July replenished moisture deficiency incurred in June and provided enough stored water to balance the deficit in August. Post-harvest loss of fruit was caused by frost damage. At both locations, the unprotected fruit was exposed to freezing temperatures on six nights in October, some as low as 26F. YIELD AND POST-HARVEST LOSS OF FRUIT 1992 Yields The average yield of six cultivars at Mt. Carmel was 77% greater (12.4 T/A) than at Windsor (7.0 T/A), Table 2. The lower yield at Windsor was due to an infection of Phytoph- thora which rotted 43-97% of the fruit of each cultivar. In comparison, pre-harvest losses due to Phytophthora at Mt. Carmel were 24-46% of the fruit of each cuhivar. While the losses at Mt. Carmel were less than at Windsor, yield of each cultivar was still about one-half of those expected. The rav- ages of Phytophthora were observed in many fields through- out Connecticut in late-summer and early-fall 1 992. Despite severe loss of fruit in many cultivars, yield of Connecticut Field exceeded 20.0 T/A at both sites. Yield of Howden exceeded 19.0 T/A at Mt. Carmel, but disease at Windsor reduced the yield to less than 10.0 T/A. The higher yield of both cultivars at Mt. Carmel and Windsor, compared to others, was attributed to some resistance to Phytophthora. 1993 Yields At Windsor, the average yield of 12 cultivars was 92% greater (26.1 T/A) than at Mt. Carmel (13.6 T/A), Table 3. The lower average yield at Mt. Carmel was due to persistent drought from June to August. Despite irrigation, the plants were stunted and the fruit matured early, in mid-August. At Windsor, local thunderstorms in July provided adequate moisture for the growing crop and the fruit matured nor- mally, in late-August and early-September. At Windsor, yield of Big Autumn, Pro Gold 500, and Connecticut Field exceeded 30.0 T/A. Big Autumn not only produced large fruit weighing 16.0 lb, but total fruit pro- duced exceeded 7,200/A. The prolific miniature pumpkins, Baby Bear and Oz, produced the most fruit, and yield ex- ceeded 12.0 T/A. Aspen was harvested after the first frost and about 30% of the fiaiit lost their handles. At Mt. Carmel, Aspen had the greatest yield despite 16% pre-harvest loss. The yield of Big Autumn, JSS 9032, and Pro Gold 500 exceeded 18 T/A. The miniature and small pumpkin cultivars. Baby Bear, Oz, and New England Pie had the greatest number of fruit/A. An infection of Phytophthora, 2 weeks before harvest, reduced the percent of fiaiit har- vested for Wizard. Table 2. Yield of pumpkins at Windsor and Mt. Carmel, 1992 WINDSOR MT. CARMEL Field Field Avg. Total* Total Storage Avg. Total* Total Storage Hvst. Wt. Yield Fruit Losses Hvst. Wt. Yield Fruit Losses % lbs. T/A #/A % % lbs. T/A #/A % Cultivar Autumn Gold 12 12.6 2.3 365 100 68 8.9 9.7 2180 30 Corm. Field 57 23.7 24.1 2035 21 76 20.5 20.8 2030 21 Ghost Rider 22 8.7 3.2 725 90 62 9.2 8.7 1890 46 Howden 24 23.7 9.5 800 27 79 17.7 19.3 2180 20 Oz 18 3.8 2.0 1090 47 68 3.6 7.0 3920 56 Wizard 3 19.0 0.7 75 100 54 3.2 8.6 1305 33 *Total yield = yield of fiiiit/75 ft. row x 72.6 (# 75-foot segments in 5445 linear feet of row/A) Connecticut Agricultural Experiment Station Bulletin 919 Table 3. Yield of pumpkins at Windsor and Mt. Carmel, 1993. WINDSOR MT. CARMEL Field Field Avg. Total* Total Storage Avg. Total* Total Storage Hvst. Wt. Yield Fruit Losses Hvst. Wt. Yield Fruit Losses % lbs. T/A #/A % % lbs. T/A #/A % Cultivar Aspen 61 14.8 24.2 3270 64 84 11.9 27.0 4520 72 Baby Bear 95 1.7 12.2 14405 41 95 1.4 4.6 6700 34 Big Autumn 87 16.0 58.5 7285 33 83 10.3 18.9 3685 66 Conn. Field 97 12.8 31.6 4940 78 82 9.5 16.4 3435 78 Ghost Rider 87 8.8 22.5 5110 88 89 9.2 15.8 3435 68 JSS 9032 95 11.4 28.3 4940 74 90 10.2 18.7 3685 70 Lumina 88 7.5 16.7 4440 45 90 8.6 6.9 1590 37 New Eng. Pie 95 4.4 14.7 6700 44 93 3.8 8.8 4605 53 Oz 96 3.4 18.2 18805 7 87 3.2 8.0 5025 78 Pro Gold 500 95 15.5 35.6 4605 53 89 13.0 18.0 2765 48 Spirit 88 9.9 26.1 5275 65 91 8.2 16.8 4105 67 W\7md 79 11.8 24.7 4190 98 39 9.9 3.7 755 78 "Total yield = Yield of fruit/65 ft. row x 83.75 (#65-foot segments in 5445 linear feet of row/A) Table 4. Losses of harvested pumpkins during 4 weeks of improtected storage. WINDSOR MT. CARMEL 1992 1993 1992 1993 % % % % Cultivar Autumn Gold 100 - 30 - Aspen - 64 - 72 Baby Bear - 41 - 34 Big Autumn - 33 - 66 Connecticut. Field 21 78 21 78 Ghost Rider 90 88 46 68 Howden 27 - 20 - JSS 9032 - 74 - 70 Lumina - 45 - 37 New England Pie - 44 - 53 Oz 47 7 56 78 Pro Gold 500 - 53 - 48 Spirit - 65 - 67 Wizard 100 98 33 78 Post-harvest loss of fruit Although harvested pumpkins should be protected from rain and frost to reduce post-harvest losses, all fruit were unprotected during October to resemble conditions in pick- your-own operations. At both locations, there were 2-4 light frosts (30-32F) and 2-3 moderate frosts (26-29F) each year. Frost damage appeared as water-soaked, discolored patches on the shoulders of the fruit. The weakened handles severed from the fiiiit when lifted. In 1992, post-harvest loss of Connecticut Field and Howden was least at both sites, Table 4. Post harvest loss of Oz averaged about 50% at each site. At Windsor, large post- harvest losses of Autumn Gold, Ghost Rider, and Wizard were due to frost damage and rotting by Phytophthora. In 1993, among all cultivars, post-harvest loss of Oz was least at Windsor but among the greatest at Mt. Carmel. At Mt. Carmel, Oz matured at least 3 weeks earlier than at Windsor and the more mature fiuit were damaged more readily. Among the large pumpkins, Big Autumn and Pro Gold 500 were less damaged by frost than Connecticut Field, Ghost Rider, and Wizard. FRUIT CHARACTERISTICS Several fruit characteristics, observed during the frials, may assist the grower in the selection of cuhivars. Table 5. These characteristics varied slightly from site to site and depended upon weather, disease, and speed of maturity. Weather and disease controlled vine health. Vmes stunted by drought or disease produced smaller finiit and thiimer han- dles. ■ WEIGHT DISTRIBUTION Commercial seed catalogues generally rate cultivars ac- cording to their weight class; i.e. 10-15 lbs, 20-25 lbs, etc. Pumpkin Trials 1992-1993 Table 5. Characteristics of pumpkin fruit (average of Windsor and Mt. Carmel) Handle Shape Color Ribbing thickness Shape Uniformity Autumn Gold Deep orange Moderate, deep Medium Globe Somewhat uniform Aspen Light orange Moderate, shallow Medium Upright globe Somewhat variable Baby Bear Orange Many, deep Thin Flattened globe Uniform Big Autumn Orange Few, shallow Medium Upright globe Somewhat variable Connecticut Field Light orange Many, deep Medium to thick Upright to globe Variable Ghost Rider Deep orange Moderate, shallow Medium to thick Upright Somewhat variable Howden Deep orange Many, deep Thick Upright to globe Variable JSS 9032 Orange Moderate, deep Thick Upright globe Somewhat variable Lumina White* Few, deep Thin Flattened globe Uniform New England Pie Deep, orange Many, deep Medium Flattened globe Uniform Oz Orange Smooth Thick Globe Very uniform Pro Gold 500 Deep orange Many, deep Thick Upright globe Uniform Spirit Light orange Few, shallow Medium Upright globe Somewhat uniform Wizard Deep orange Many, deep Medium Globe Uniform ♦Overmature or stressed fruit may develop a grayish-green cast. Table 6. Percent distribution among weight classes (lb) of pumpkin fruit at Windsor and Mt. Carmel. The underlined numbers represent the median weight class. WINDSOR MT. CARMEL <5 5-10 10-15 15-20 20-25 >25 <5 5-10 10-15 15-20 20-25 >25 Cultivar Autumn Gold - 40 20 20 20 - 13 5Q 37 - - - Aspen - 21 40 21 18 - 6 28 42 20 2 2 Baby Bear 100 - - - - 100 - - - - - Big Autumn 3 11 30 20 21 5 14 34 26 14 2 - Connecticut Field* - 23 30 17 14 16 4 28 25 22 13 8 Ghost Rider* 14 47 33 3 3 - 15 41 30 9 1 - Howden - - 9 18 18 ^ - 13 17 22 27 10 JSS 9032 12 22 42 15 2 2 16 26 30 14 4 - Lumina 15 72 13 - - - 10 52 37 - - - New England Pie 76 24 - - - - M 16 - - - - Oz* 100 - - - - - 100 - - - - - Pro Gold 500 - 13 42 26 15 4 6 25 2G 30 9 - Spirit 10 42 38 3 6 - 16 62 16 6 - - Wizard* 10 24 41 20 5 - 4 33 20 33 - * Average of 2 years These catalogue ratings are very general and represent aver- age weights attained by pumpkins growing under favorable temperature, moisture, nutrient supply, and freedom from disease. In my trials each cultivar produced a population of fruit that encompassed several weight classes. Table 6. In 1993, the median weight classes of Autumn Gold, Big Autumn, Howden and JSS 9032 were one class greater at Windsor than at Mt. Carmel, the result of a more favorable supply of moisture. Clearly, at Windsor, Howden produced the heaviest fruit followed by Big Autumn. The medians of Aspen, Autumn Gold, Connecticut Field, JSS 9032, Pro Gold 500, and Wizard were in the 10-15 lb class at both sites. As Connecticut Agricultural Experiment Station Bulletin 919 expected, Baby Bear, New England Pie, and Oz mostly fell in the <5 lb class at both sites. The medians of Aspen, Con- necticut Field, Ghost Rider, JSS 9032, Lamina, Pro Gold 500, and Wizard fell one or two weight classes below those reported in commercial catalogues. These lower medians were imdoubtedly due to unfavorable growing conditions in 1992 (too wet) at both sites and 1993 (too dry) at Mt. Carmel. In 1993, the greater plant population increased the average yield/A of most cultivars, but the fruit size was smaller. MANAGEMENT STRATEGIES Site selection In 1 992, average yields of all cultivars at Mt. Carmel was 10,800 lb/A greater than at Windsor; in 1993, it was 25,000 lb/A less. Although the yields of pumpkins in 1992 and 1993 were highly dependent upon weather and disease control, the fine sandy loam soils at Mt. Carmel provided a greater mois- ture holding capacity than the sandy soil at Windsor. Sandy soils require more frequent light irrigations than loamy soils. An important consideration is the location of the field. Growing sites that permit good air movement are less sus- ceptible to disease infections than small fields surrounded by tall trees that inhibit air movement. Pumpkins in fields at the base of narrow valleys are more susceptible to damage by early frosts than in fields on upper slopes. Pick-your-own fields are at greater risk in low-lying areas where early frosts are known. Selection of cultivars The ideal cultivar produces a high yield of uniformly shaped fruit and withstands damage from frost and disease. Some growers report that their customers prefer a somewhat upright globe-shaped fhiit that is deep orange in color. For pumpkins exceeding 20 lbs, Howden has the greatest yield, followed by Connecticut Field. The fruit of Connecticut Field is more variable in size than Howden and has more fruit with flat surfaces. For pumpkins in the 10-20 lb range. Big Autumn, JSS 9032, and Pro Gold 500 had excellent yields. Pro Gold 500 was more uniform in shape, had thicker handles, and greater durability in unprotected storage than Big Autumn or JSS 9032. Big Autumn, with its precocious yellow gene, had yellow coloration at the base of its handle and post-harvest loss due to frost damage was greater than Pro Gold 500 or JSS 9032. Among the cultivars weighing less than 5 lbs, Oz had the greatest yield and uniformity of fruit. Its post-harvest loss was variable. Baby Bear and Oz were the most prolific pro- ducers of fhiit. The fruit of Oz weighed twice as much as Baby Bear. Insect and disease control Pumpkin fruit and vines are highly susceptible to disease and infestation by vine borers and cucumber beetles. For disease confrol, regular applications of fungicides, especially during periods of cool, wet weather, were necessary to insure greater yield of fhiit. In fields where black rot and Phytoph- thora are known, pre-plant incorporation of fungicide may be necessary. Additional applications of ftingicides every 7-10 days to developing vines and fhiit in late-June through Au- gust should control infection. If cucumber beetles and vine borers have been observed in late-June, insecticides applied weekly through mid- July will control populations until they naturally decline. Post-harvest storage Pumpkins can be stored at 50-55F and 70-75% relative humidity for several months (Ashley 1992). For 3-4-week storage prior to Halloween pumpkins can be placed in a dry area where temperatures do not fall below 32F or covered with plastic sheets or tarpaulms to protect them when frost threatens. Fruit left in the field for pick-your-own clientele cannot be protected from frost. Selection of cultivars that are more resistant to frost damage is an alternative. Among the large and medium size pumpkins, Howden, and Pro Gold 500 lost fewest fruit to frost damage. The miniature pump- kin, Baby Bear, was more resistant to frost damage than Oz. REFERENCES Ashley, R.A., et al. 1992. New England vegetable manage- ment guide. Cooperative Extension New England Regional Publication. 96p. Splittstoesser, W.E. 1979. Vegetable growing handbook. AVI Publishing Company, Westport, Cormecticut. 298p. Yamaguchi, M. 1983. World vegetables: principles, produc- tion, and nufritive values. AVI Publishing Company, West- port, Connecticut. 415p. University of Connecticut Libraries 39153G28938480