Our objective was to increase the percentage of marketable red fruit at harvest time on paprika pepper (Capsicum annuum L.) plants intended for mechanical harvest by using ethephon [(2-chloroethyl)phosphonic acid] to remove late-developing blooms and green fruit. We conducted three experiments on field-grown plants in southwestern Oklahoma. We tested ethephon solutions of 0, 1000, 2000, 3000, and 4000 μl·liter–1 as a one-time foliar application on various dates. Total dry weight of harvested fruit decreased linearly with ethephon rate in all three studies. Marketable fruit as a percentage of total harvested fruit weight increased linearly with ethephon rate in two studies. There was no consistent effect of ethephon on the intensity of red pigment extracted from dehydrated marketable fruit. With proper timing, as little as 1000 μl ethephon/liter was enough to alter the distribution of total harvested fruit weight toward marketable fruit and away from green fruit. A target spray “window” of the last 10 days in September seemed appropriate for southwestern Oklahoma, and the recommended rate of ethephon was between 2000 and 3000 μl·liter–1.
James E. Motes, Brian A. Kahn and Niels O. Maness
Jeffrey G. Williamson and William O. Cline
-harvested fruit. They concluded that the inability to remove bruised fruit during grading and sorting presented serious problems for maintaining quality during storage. Similar reductions in marketable yield from mechanical harvesting were reported in Michigan by
Troy A. Larsen* and Christopher S. Cramer
New Mexico onion production will begin using mechanical harvesters in the near future in order to stay competitive in today's market. Past onion breeding objectives have focused on improving onions for hand harvesting instead of mechanical harvesting. Our breeding program is starting to evaluate germplasm for bulb firmness. The objectives of this study were to evaluate hybrid lines for their bulb firmness, to compare two methods of measuring bulb firmness, and to compare bulb firmness using two different production schemes. Bulb firmness of spring-transplanted and spring-seeded intermediate-day hybrid breeding lines was measured using a digital FFF-series durometer and a subjective rating of firmness achieved by squeezing bulbs. Bulbs were rated on a scale of 1 (soft) to 9 (hard). In general, these hybrid lines produced very firm to hard onions whether the lines were transplanted or direct-seeded. Bulb firmness of these lines measured with the durometer was greater when the lines were direct-seeded (74.9) than when transplanted (73.5). Conversely, when firmness was measured with our subjective rating, transplanted onions exhibited slightly greater firmness (8.9) than direct-seeded onions (8.8). For both transplanted and direct-seeded onions, durometer readings were weakly correlated in a positive fashion with our subjective rating. In general, durometer readings gave a greater spread in firmness measurements with a range of 69.6 to 77.8 in firmness values. Subjective ratings of bulb firmness ranged from 8.5 to 9.0. Depending on the firmness of evaluated breeding lines, our subjective rating system should be adjusted to better distinguish firmness differences between bulbs.
Griffin M. Bates, Sarah K. McNulty, Nikita D. Amstutz, Victor K. Pool and Katrina Cornish
Rubber dandelion (Taraxacum kok-saghyz, Rodin) is being developed as a temperate-zone source of rubber, but best agronomic practices must be determined before it can become a viable supplement to imported rubber produced from para rubber tree (Hevea brasiliensis, hevea) plantations located mostly in Southeast Asia. In our study, the effect of planting density and harvest time on yield was determined by transplanting 1.5-month-old greenhouse-produced plants at planting densities of 1.24, 2.47, 4.94, and 9.88 million plants/ha, randomized across four planting boxes with two densities per box (i.e., two planting areas at each density). Half of each planting area was selected randomly and hand-harvested after 6 months, and the remaining plants were hand-harvested after 1 year. Rubber yields per plant were greater after 1 year than after 6 months, but yields per unit area were similar as a result of the loss of half the plants during the severe 2013–14 Ohio winter. A maximum rubber yield of 960 kg dry rubber/ha was obtained from the 9.88 million-plants/ha planting density after 1 year, but root size was significantly decreased compared with lower densities, and appeared too small for mechanical harvest. A planting density between 2.47 and 4.94 million plants/ha may produce the optimal combination of root size and total rubber yield. Greater rubber concentrations, faster-growing plants, short-season germplasm, and in-field weed control are required before yields obtained in outdoor planting boxes can be matched or exceeded on farms, especially in a direct-seeded rubber dandelion crop.
Mark A. Bennett, David M. Francis and Elaine M. Grassbaugh
Ethephon (2-chloroethyl phosphonic acid) has been widely used under field conditions as a growth regulator to trigger the ripening of processing tomatoes prior to mechanical harvesting. Recent interest in whole-peeled and diced tomato products has raised questions about ethephon rates, and possible split applications for top quality. This 3-year field study tested two commercial cultivars of processing tomatoes (`OH8245' and `P696') and the effect of various ethephon applications on fruit firmness, color uniformity, and peeling variables. Transplants were established in mid to late May of 1996–1998 on raised beds in single rows at the OSU/OARDC Veg. Crops Branch in Fremont, Ohio. Ethrel applications for each cultivar were: 0, 0.58, 0.58 × 2 applications, 1.17, 1.17 × 2 applications, 1.75, 2.34, 4.68, and 7.02 L·ha–1. Fruit were tested for firmness, color uniformity, pH, titratable acids, and soluble solids. Samples from ethephon treatments of 0, 1.17 × 2 applications, 2.34, 4.68, and 7.02 L·ha–1 were peeled and canned for color inspection and firmness after 18 months storage. Three-year data for red fruit yield showed a typical response to increasing amounts (0 to 7.0 L·ha–1) of applied ethephon. While high rates (4.7 or 7.0 L·ha–1) gave some of the highest red fruit yields, and the greatest percent red fruit values, high rates were also linked with among the lowest fruit solids values. Split application comparisons showed little influence on quality variables examined in this study. However, chroma values were improved (more vivid color) when 2.3 L·ha–1 was applied vs. 1.17 L·ha–1 applied twice. Split applications also tended to produce softer fruit. Our results suggest that single ethephon applications of 1.17 to 2.34 L·ha–1 provide optimal fruit ripening and quality under midwestern U.S. conditions.
David A. Bender, J. Wayne Keeling and Roland E. Roberts
Large weeds, particularly amaranths, are a serious impediment to mechanical harvesting of jalapeno peppers. Several herbicides were applied in 1998 and 1999 postemergence topical (PT) to commercial fields when peppers had four to six leaves, or postdirected (PD) with a shielded sprayer ≈1 month later, and evaluated for crop injury, weed control, and effects on yield. Treatments were applied to four-row plots 9 m long with a CO<subscript>2 backpack sprayer. PT treatments included pyrithiobac sodium at 0.036, 0.053, or 0.071 kg·ha–1 a.i. with nonionic surfactant or crop oil concentrate, metolachlor at 1.68 kg·ha–1 a.i., and oxyfluorfen at 0.14 or 0.28 kg·ha–1 a.i.. PD treatments consisted of the same rates of pyrithiobac sodium with nonionic surfactant only, and the same rates of oxyfluorfen. Pyrithiobac sodium PT caused significant chlorosis (reduction in SPAD chlorophyll) in new foliage and reduction in plant height after 1 week, but plants recovered with no effect on final plant height, chlorophyll, or yield. No significant difference was observed between the two adjuvants. Metolachlor had no measurable effect on pepper growth or yield. Oxyfluorfen PT killed young apical tissue and caused chlorosis of immature leaves. Plants recovered, but plant height was reduced by 14% to 28% and yield by 11% to 43%. PD treatments had no effect on pepper growth or yield. All herbicides provided adequate weed control under light pressure. Pyrithiobac sodium appears to have potential as a postemergence herbicide for control of amaranth in jalapeno peppers.
Richard L. Fery, Blair Buckley and Dyremple B. Marsh
Home gardeners and farmers in the southern United States have traditionally grown southernpeas to produce both fresh-shell peas and immature, fresh pods, or snaps. American growers do not presently have access to a single variety that is ideally suited for both uses. In 1988, a plant breeding effort was initiated to incorporate genes conditioning superior yield and seed characteristics of Asian “vegetable cowpeas” into American snap-type southernpeas. This effort resulted in the development of `WhipperSnapper', which is suited for use as a dual-purpose variety that can be used to produce both snaps and fresh-shell peas. Typical ready-to-harvest `WhipperSnapper' snaps are green colored, 6.4 mm in diameter, 7.6 mm in height, and 24 cm long. Typical mature-green pods suitable for fresh-shell harvest exhibit an attractive yellow color, are 25 cm long, and contain 14 peas. Fresh peas are cream-colored, kidney-shaped, and weigh 24.5 g per 100 peas. Dry pods exhibit a light straw color, and the dry peas have a smooth seedcoat. The total `WhipperSnapper' yield of snaps can be as much as 62% greater than the total snap yield of the snap-type variety `Bettersnap'; pea yield can be as much as 69% greater. The quality of `WhipperSnapper' seed is excellent and much superior to that of `Bettersnap'. `WhipperSnapper' can be used by home gardeners and market gardeners to produce abundant quantities of snaps and fresh-shell peas during seasons too hot for successful culture of such table legumes as snap beans. `WhipperSnapper' also has the potential for use as a mechanically harvested source of snaps for use by food processors in mixed packs of peas and snaps.
W. Letchamo and A. Gosselin
Camomile (Chamomilla recutita Rauschert) is an annual plant from the Asteraceae. Camomile is one of the most frequently used medicinal plants, and has a commanding place in the world market. The flower heads are used in pharmaceutical preparations, and the cosmetic and beverage industries. The extracts from camomile flowers, to mention some, are known to have the most-effective sedative (3.29× compared to papaverin), antidepressive, tumor -protective, antiinflammatory, and accelerative properties in the regeneration of skin tissues. It is considered a panecia, due to its strong effects among many others, in the treatment of gastric ulcers, stomatology, respiratory complications, nephritis and nephrolithiasis (dilution of the kidney stones), and urinary bladder stones (cystolithiasis). Recently, successful research programs have been carried out to develop new camomile varieties with higher flower yield and better content of the active substances, suitable for mechanical harvesting under conventional cultivation. Apart from growing consumer demand for organically grown herbal products, the use of some herbicides and insecticides has resulted in the shifts of the content of active substances. The yield stability, content, and composition of the active substances under organic cultivation, particularly in areas with extreme climatic conditions, such as northern North America, should be investigated. We identified and introduced new camomile varieties and studied their suitability for organic field cultivation in Quebec, Canada. We studied over-wintering ability, yield potentials, and the content and composition of essential oil, flavonoids, and coumarins under field conditions. The physiology of the new varieties, particularly the relationship between photosynthesis and yield formation, and the accumulation of the active substances under different cultivation conditions remain to be studied.
Robert C. Hansen, Kenneth D. Cochran, Harold M. Keener and Edward M. Croom Jr.
A natural product known as taxol has been approved by the FDA for treatment of ovarian and breast cancers. In addition, preliminary clinical studies have shown encouraging results when using taxol to treat melanomas, lung, head, and neck cancers. Ornamental yews have been identified as a potential renewable source of taxol and related taxanes. Commercial nurseries were surveyed during Summer and Fall 1991 as a basis for estimating populations of Taxus cultivars currently growing in the United States. Clippings of selected cultivars were sampled from nursery fields in Ohio and Michigan to estimate expected clippings yields as a function of cultivar and cultivar age. More than 30 million Taxus plants were reported to be grown by the 19 major nurseries that responded to the survey. About 88% of all Taxus plants reported in the survey were grown in the three-state area of Ohio, Michigan, and Pennsylvania. Taxus × media `Densiformis', `Hicksii', and `Brownii' were found to be grown by nearly all nurseries in the survey; more than half grew T. × media `Wardii' and T. cuspidata `Capitata', while other well-known cultivars seem to have been specialties of one or two nurseries. Annual clippings yields on a dry-weight basis (db) ranged from ≈20 g/plant to 140 g/plant. Expected yields were found to be very dependent upon plant age and cultivar. Taxus × media `Hicksii' appeared to be the most ideal ornamental yew that could provide a renewable source of taxol because of immediate availability and potential for mechanical harvesting of upright clippings. An estimated 3000 to 4000 ovarian cancer patients could be treated annually with the taxol currently available for extraction from T. × media `Hicksii' clippings.
Silvia G. Mauri, H.C. Bittenbender, Kent D. Fleming and Loren D. Gautz
Marketable coffee (Coffea arabica) yield and cost of production under two systems of mechanized pruning—hedging and stumping— were investigated. Data were collected from 1997 to 2001—a single pruning cycle—on three cultivars on three farms on Kauai, Maui, and Molokai. Treatments were variations of hedging and stumping, including time of pruning, methods of re-growth control, and tree in-row spacing were applied to each coffee cultivar. Economic evaluation was based on a partial budget analysis of the actual costs per year of the different pruning systems used on each farm. Mechanical pruning costs per acre for best hedging and stumping treatments across cultivars were 90% and 83% less, respectively, than the current practice of manual pruning. Response to pruning system varied according to coffee cultivar, tree in-row spacing and farm location. The tall cultivar Mokka had higher yields when hedged at 5 ft (1.5 m) tall and 5 ft wide, and the semi-dwarf cultivar Yellow Catuai had higher yields when stumped at 2 ft (0.6 m) tall. Hedge pruning should be done early in the year, January to February, for the semi-dwarfs, `Yellow Catuai' and `Red Catuai', but can be delayed until May for `Mokka'. Annual topping in the hedging systems should be done January to May for `Yellow Catuai' but maybe delayed until May for `Mokka' and `Red Catuai' without yield loss. The economic evaluation revealed that the cost of stumping was higher than hedging. For `Yellow Catuai' on Kauai the economic evaluation indicated that although the cost of stumping was higher, the accompanying higher yields resulted in a higher gross margin for this system. When stumping, verti- cal branches can be set with a contact herbicide spray to avoid higher hand pruning costs without lowering yields. Stumps should be narrowed after stumping if spaced, 2.5 ft (0.75 m) the current standard in-row spacing for mechanical harvesting. Wide in-row spacing (5 ft) should be considered by growers when planting or re-planting.