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Kent Cushman and Crofton Sloan

A circular garden, divided into eight sections or “slices,” was established for the purpose of demonstrating agriculture to youth. Each section of the garden represents a form of agriculture associated with the consumption of pizza. Soybeans were planted to represent oil, wheat to represent flour, vegetables to represent tomato sauce and vegetable toppings, herbs to represent spices, and pine trees to represent paper and cardboard products. A dairy cow, beef cow, and pig were fenced within separate sections to represent cheese, beef, and pork, respectively. The idea originated in Madera, Calif., from Thank-a-farmer, Inc. and was used with permission. The garden is an ongoing cooperative effort between research and extension personnel of Mississippi State University, local county officials, and area schools. The project has garnered support from the Mississippi Cattle Industry Board (start-up and maintenance funds), Heritage Vinyl Products (fencing), D.P. Fence Co. (construction), and Dominoe's Pizza (pizza lunches for the youth). We anticipate at least 1000 school children to visit the “Pizza Farm” each year, and we expect the community to continue to support and take pride in this project.

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Kent Cushman* and Muhammad Maqbool

The American mayapple (Podophyllum peltatum L.) is native to eastern North America and its leaves contain the pharmaceutical compound podophyllotoxin. Podophyllotoxin is used in the manufacture of several types of drugs used in the treatment of cancer, arthritis, and various skin conditions. With leaves being a renewable resource, the plant is a candidate for cultivation by growers of specialty crops. We are investigating strategies of establishing mayapple in field plantings. Rhizome segments were harvested from the wild and immediately transplanted to raised beds in northern Mississippi. There were three planting times, Fall 2000, Spring 2001, or Summer 2001, and three propagule types: (1) two-node rhizome segments with a terminal node and its adjacent one-year-old node, referred to as Nt+N1, (2) one-node segments with a single node, other than Nt, of unknown age, referred to as Nx, or (3) one-node segments with a single terminal node, referred to as Nt. Each spring, shoots emerged from the ground in March, grew during April, and senesced throughout May. Shoot emergence, leaf area, leaf dry mass, and shoot height were recorded each spring. Plant growth and performance can be ranked as follows. EXCELLENT: Spring-planted Nt+N1. GOOD: Fall- and summer-planted Nt+N1; fall-, spring-, and summer-planted Nx; and spring-planted Nt. FAIR: Fall-planted Nt. POOR: Summer-planted Nt. We can now recommend all three planting dates, but in the following order of preference: spring > fall > summer. We can also recommend two of the three propagule types, also in the following order of preference: Nt+N1 > Nx. The Nt propagules performed adequately when planted during fall or spring, but they did not perform well when planted during summer.

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Kent Cushman and Muhammad Maqbool

American mayapple (Podophyllum peltatum) is being investigated as a domestic, renewable, and alternative source of podophyllotoxin, a precursor compound used in the manufacture of several drugs. Indian mayapple (P. emodi) is the current source of the compound. The objective of this study was to examine growth of transplanted rhizome segments of American mayapple at four transplant times during the year. Two-node rhizome segments were carefully dug with roots intact from naturally occurring wild populations near Holly Springs, Miss. Segments were dug in Oct. 2002, Dec. 2002, Feb. 2003, or June 2003. Within 1 day of each harvest, segments were transplanted into 1-gal pots containing a mixture of sandy soil and a finely ground pine bark mulch. Pots were then set in a raised bed, such that the soil surface within the pots was even with that of the plant bed. Pots and plant bed then received a 3-inch layer of pine bark mulch. Rhizome segments were harvested from pots four times during the year following the date of transplant. Rhizome and roots were separated according to new or old growth and then dried. Rhizome segments transplanted during October and December increased about 36% in dry mass during the 1-year period after transplant. This was significantly greater than an increase of 12% for segments transplanted during June. Segments transplanted during February performed intermediately, increasing by 22%. Our results show that rhizome segments of American mayapple performed better when transplanted during fall and winter compared to those transplanted during summer. Segments transplanted during spring performed intermediately.

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Kent Cushman, Jin Huan, and Lisa Cushman

Grafting of watermelon scions onto squash or pumpkin (Cucurbita), bottle gourd (Lagenaria), wax gourd (Benincasa), or watermelon (Citrullus) rootstocks is practiced in most of the major watermelon production regions of the world. Advantages of grafting are protection against soilborne diseases, resistance to nematodes, and overall increased vigor of plants resulting in higher yield and better fruit quality. Disadvantages include increased cost of seedling production and the potential of altered horticultural characteristics of cultivars used as scions. With problems associated with watermelon vine decline in recent years in Florida and the increasing cost of soil fumigants, the use of grafted watermelon seedlings should be explored. Four grafting techniques for watermelon are common: splice, side insertion, approach, and hole insertion. The approach graft, though labor intensive, doesn't require exacting control of temperature and humidity after making grafts and may be well suited to south Florida conditions. All other grafts require excellent control of the post-grafting environment and a careful transition from low light and high humidity to high light and low humidity. A preliminary evaluation of grafted and ungrafted plants during Fall 2005 compared `Tri-X 313', `Palomar', `Precious Petite', and `Petite Perfection' on several rootstocks. Most rootstock/scion combinations produced fruit of normal size, appearance (internal and external), and soluble solids content. Some combinations resulted in irregular, pumpkin-shaped fruit and slightly higher incidences of hollowheart.

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Kent E. Cushman and Muhammad Maqbool

Leaves of american mayapple (Podophyllum peltatum L.) contain podophyllotoxin, a compound of interest to the pharmaceutical industry. Cultural practices for establishment of mayapple in field plantings for commercial harvest have not been investigated. A factorial arrangement of three planting dates (Fall 2000, Spring 2001, or Summer 2001) and three propagule types (Nt+N1, Nt, or Nx; as described by Maqbool et al., 2004) were used to investigate strategies for establishing mayapple plantings. Rhizome segments were harvested from the wild and transplanted into plant beds in full sun in northern Mississippi. Plant emergence was recorded during March and April of each year from 2001 to 2004. Leaves within each plot were harvested as soon as they began to yellow, from the third week of April to the first week of June each year. Propagule type and planting time interacted to affect subsequent plant growth when measured on an area basis (per square meter of growing area). In 2004, spring-planted Nt+N1 produced more shoots with greater total leaf area and dry mass than spring-planted Nx or Nt. In contrast, Nt+N1 transplanted during fall or summer was equal in performance to that of Nx or Nt. Performance of summer-planted Nt was poor, producing far less leaf area and dry mass than any of the other treatment combinations. On a per plant basis, fall-planted propagules produced greater leaf area and dry mass in 2004 than spring- or summer-planted propagules, and Nt+N1 produced greater leaf area than Nx or Nt. The effect of year was not analyzed in this study due to complications of the experimental design. In conclusion, overall plant growth and performance of spring-planted Nt+N1 can be recommended as excellent and that of fall-planted Nt as poor. All other treatment combinations can be recommended as good. These results will assist growers of specialty crops in establishing mayapple plantings under field conditions in full sun.

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Teresa Olczyk, Kent Cushman, and Waldemar Klassen

Okra (Abelmoschus esculentus) is grown as a direct-seeded cash crop at high plant populations (>87,000 plants/acre) on calcareous soils in Homestead, south Florida. A study was established in a commercial field in May 2005 to evaluate if high populations translated to higher yields. Seedlings were thinned to within-row spacings of 2, 4, 6, 8, and 10 inches in rows set 3 ft apart (87120, 43560, 29040, 21780, and 17420 plants/acre). Harvest data was collected from 29 July to 30 Sept. 2005 (26 harvests) from 10 ft of the center row within plots 15 ft long and 3 rows wide. Decreasing plant density resulted in decreasing plant height early in the season and increasing height late in the season. Density affected stem caliper with a clear trend of decreasing density and increasing caliper. Early, mid-, and total yields by weight (boxes/acre) were not affected by density, but plants at the lowest density produced 55% more late yield than plants at the highest density. Plants at the lowest density produced 30% fewer early pods and 31% more late pods than plants at the highest density. Decreasing plant density resulted in increasing average pod weight for early, late, and total harvests by as much as 14% to 18%. With inexpensive open pollinated cultivars such as `Clemson Spineless 80', there seems little economic incentive to reduce plant populations below what is commonly used in the Homestead area. Growers should not be alarmed, however, if plant stands are reduced to some extent after seeding.

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Kent E. Cushman and Thomas E. Horgan

Mississippi growers produce southernpea for the fresh market on raised beds using 20 to 30 lb/acre nitrogen. This study compared conventional production practices to alternative approaches in a 3 × 2 × 2 factorial arrangement in a randomized complete-block design with four replications. Three cultivars of southernpea, `Quickpick' (QP), `Texas Pinkeye' (T × PE), and `Mississippi Pinkeye' (MsPE), were planted into either raised or flat beds using either 30 lb/acre ammonium nitrate without seed inoculation or no ammonium nitrate with Rhizobium seed inoculation. QP and T × PE were harvested with a one-row Pixall harvester and MsPE was hand harvested. All plots were harvested at the mature-green stage. Yields were reduced due to drought conditions during pod fill. MsPE was hand harvested only once due to dry conditions and less-than-ideal yields. QP produced significantly greater yield (1208 lb/acre) than T × PE (962 lb/acre) or MsPE (981 lb/acre). The two nitrogen treatments were not significantly different. QP and T × PE were not affected by bed architecture, but MsPE on raised beds yielded significantly more than on flat beds. As with a similar study in 1998, also under nonirrigated conditions, MsPE had a significantly greater shellout than QP or T × PE. There were no significant interactions for yield or percent shellout.

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H. Brent Pembcrton and Kent E. Cushman

Basal sucker shoots between 15 and 30 cm tall on multi-branched, tree-form crape myrtles (Lagerstroemia indica) were sprayed to run-off with NAA solutions of 0, 0.5, 1.0, and 1.5% in June. Five weeks later, sucker growth was assigned a visual rating from 0 to 4 denoting 0 to 100% control. Heights of three basal shoots were measured for each plant as another indicator of control. Visual ratings increased linearly from 1 to 3.6 as NAA increased from 0 to 1.5%. Basal shoot height decreased quadratically with increasing NAA concentration with the 1.0 and 1.5% NAA treatments resulting in a 53% reduction when compared to the control. Further work is needed to assess the effect of NAA on flowering and to determine if spring applications will result in season long control.

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Kent E. Cushman and Theodore W. Tibbitts

Chlorosis and necrotic spotting develop on the foliage of particular cultivars of potato (Solanum tuberosum L.) when grown under constant light. `Kennebec', a cultivar severely injured by constant light when propagated from tissue-cultured plantlets, also was injured when plants were propagated from small tuber pieces (≈1 g). However, plants did not develop injury when propagated from large tuber pieces (≈100 g). Plants from large tuber pieces grew more rapidly than plants from small tuber pieces. The role of plant vigor and carbohydrate translocation in controlling injury development is discussed.

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Kent Cushman, Ted Tibbitts, Marc Anderson, Walt Zeltner, and Xianzhi Fu

A reactor designed to catalyze ethylene to carbon dioxide and water in the presence of UV radiation was tested under a wide range of conditions applicable to horticulture. The reactor was constructed of a hollow stainless steel housing into which a 4-W UV lamp was inserted. Fourteen grams of zirconia-titania catalyst crystals, particle size 0.50 to 0.75 mm, filled the space between lamp and housing. Polysulfone end caps sealed the unit on each end and provided fitting by which air was directed in one end and out the other. Increasing dewpoint temperature (5, 11, 17, and 22C) resulted in decreasing ethylene removal. Increasing reactor temperature (20, 30, 40, 60, and 80C) resulted in increasing ethylene removal. Increasing air flow (106, 255, 385, 665, 1000, and 2000 ml·min–1) resulted in a decreasing proportion of ethylene removed from the air stream but an increasing total amount of ethylene catalyzed per unit time (μl·day–1). Increasing ethylene concentration (65, 147, 260, and 1131 ppb) resulted in increasing ethylene removal. The reactor performed well under all these conditions, and these data will be used to design ethylene removal systems for a wide variety of horticultural applications.