Plant and Environmental Protection Sciences

Pink root (Phomaterrestris) is among the major limiting factors for the production of sweet onions on Maui, Hawaii. Few management options exist for the control of pink root in onions. Two split-plot experiments were conducted in the area of Kula, Maui, over 2 years to evaluate several alternative management practices. In Expt. 1, the main plots were a rotation with cabbage, solarization with a clear plastic mulch, and a fallow period. Subplots were plus or minus Vapam fumigation. Sub-subplots were biomass application of Sudex or rape, inoculation with an EM biostimulant, and control. Each treatment had four replications for a total of 96 plots. In the follow-up experiment, the main plots were Vapam fumigation, rotation with either a Sudex or rape cover crop, and controls. The subplots were plus or minus EM biostimulant application. In Expt. 1, three separate treatments: solarization, cabbage rotation, and Sudex incorporation had a synergistic effect with Vapam fumigation. Fumigatio...

Regulatory agencies are concerned about the high levels of P fertilizers used in some agricultural areas because of potential runoff to aquatic habitats. Farmers in Hawaii traditionally make blanket P applications even in soils high in P. Many farmers, especially those growing leafy crops, claim to observe responses to P, especially during the cooler winter months. A series of 15 field experiments were conducted over a 2-year period to evaluate the response of three mustard cabbage varieties to five P fertilizer rates across three locations in the state, and across several planting seasons. All experiments were conducted in soils with P levels that the University of Hawaii determined to be high in P. The experimental design for each experiment consisted of three commercial mustard cabbage varieties, and five P application rates (from 0 to 400 kg·ha-1 of TSP). Each plot consisted of a 3-m double-row, with plants spaced 15 cm within the row, and 30 cm between rows, with four replicati...

The use of living mulches to reduce the density of silverleaf white¯y, Bemisia argentifolii Bellows and Perring, and melon aphid, Aphis gossypii Glover, and the conveyances of aphid-transmitted virus, papaya ringspot virus-watermelon strain (PRSV-W), and squash silverleaf disorder on zucchini, Cucurbita pepo L. was evaluated during 1995 and 1996 in Oahu, Hawaii. Living mulches used were buckwheat (Fagopyrum esculentum Moench) and yellow mustard (Sinapis alba L.). Mean densities of aphids were signi®cantly lower in zucchini grown with living mulch both years of the study. In contrast, white¯ies were lower only during the second year. The severity of squash silverleaf disorder was signi®cantly higher in bareground zucchini compared with living mulch-diversi®ed zucchini during both experiments. The percentage of zucchini plants displaying PRSV-W during the early season was signi®cantly lower on zucchini grown in living mulches during both years of the study. The delay in PRSV-W in living mulch resulted in a higher percentage of fruits by weight displaying viral symptoms in bareground zucchini. Reductions in pest activities in living mulch-diversi®ed zucchini resulted in higher marketable yields only during one year of the study.

Climatic requirements 1 Cultivars 1 Soils and fertilizers 2 Soil type, nutrient rates and fertilizer placement, plant tissue analysis Culture and management practices 4 Time to plant, field preparation, propagation, transplanting, irrigation, hydroponic production Pest control 6 Insects 6 Aphids, beet armyworm, black cutworm, cabbage looper, corn earworm, leafminer, nematodes, mites, thrips, whiteflies Diseases 8 Bacterial leaf spots, beet western yellows, bolting, bottom rot, brown stain, brown rib or rib blight, crown and head rot, damping off, downy mildew, drop, lettuce mosaic virus, pink rib, russet spotting, soft rot, tomato spotted wilt virus, tip burn Weeds : 14 Harvest and postharvest practices ~14 Harvest timing, production yields, harvesting, handling practices, shipping and storage, market information Selected references Tables 1. Lettuce cultivars recommended for Hawaii 2. Recommended nutrient ranges for lettuce 3. Plant spacings for lettuce in Hawaii 5 4. Host ranges of Pseudomonas, Xanthomonas, and Erwinia in Hawaii 5. Duration of lettuce growth period 6. Average yields of lettuce in Hawaii 1 Table 1. Lettuce cultivars recommended for Hawaii. Type Head Semi-head Romaine Green leaf Royal Oak leaf Red leaf Endive (escarole) Planting season Nov.-Feb.

Sweetpotato, Ipomoea batatas, a member of the morning glory family, originated in South Mexico and Central America, and is now the seventh most important food crop, worldwide. Sweetpotatoes, along with taro, were the major staples for the early Hawaiians since 500 BC. Commercial cultivation in the islands began in 1849. In 1919 sweetpotatoes were considered 10th in value among agricultural crops in Hawaii when grown as an emergency crop during the war years. By 1948, the farm-gate value for sweetpotatoes was $100,000. The sweetpotato is grown for its enlarged roots which can be boiled, baked or fried, or processed into chips. The stems and tips may also be boiled or fried for use in soups or salads. Both roots and foliage can also be grown as feed. The 1991 farmgate value for sweetpotatoes in Hawaii was about $600,000, and is presently planted and harvested year-round throughout the state, with production acreage primarily in Molokai. Sweetpotato has a wide adaptability to Hawaii's environments and has a high content of vitamins beta carotene and ascorbic acid. In addition, the young leaves, common in some oriental and Filipino dishes, have a 25-33% protein content on a dry weight basis. Climate Short days promote fleshy root development and flowering, while long days promote top growth. The optimum soil temperature range for fleshy root development is 70-80F (21-28C). Optimum growing temperatures for top growth are >77F (>25C), but it can be grown at altitudes of up to 2,000 ft. The sweetpotato is considered to be drought tolerant, but the first 40 days after planting are the most sensitive to deficits in irrigation. Sweetpotato yields in sandy loam soils with 25% moisture content will generally be similar or greater than yields in soils with 40, 60, and 80% moisture content. Most cultivars are susceptible to waterlogging and to water tables <1.5 ft (<0.5 m). The sweetpotato tolerates ranges of 20-50

Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the US Department of Agriculture. Andrew G. Hashimoto, Director/Dean, Cooperative ...

Pakistan, is an excellent green manure crop. It grows exuberantly, reaching a height of 6 ft (1.8 m) within 90 days. Its ability to rapidly add nitrogen and organic matter to over-farmed soils makes it a favorite for improving soil quality and rejuvenating fields. The cultivar ...

Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the US Department of Agriculture. HM Harrington, Acting Director/Dean, Cooperative ...

The important tropical root and tuberous crops cassava (Manihot esculenta). sweet potato (Ipomoea batatas), yams (Dioscorea spp.) and the aroids (especially Xanthosoma and Colocasia spp.) represent an important source of relatively inexpensive carbohydrates to large sectors of the population in tropical areas. One or more tropical root crops are normally a staple in rural communities and are typically grown on small-scale subsistence farms. The current status of the agroecology research on these crops. including productivity under polyculture systems. resource (water, nutrients, light, space) utilization, tolerance to environmental stress, pest dynamics response to habitat manipulation, and alternative cultural practices, is reviewed in this paper as they relate to the performance of these crops in small-scale tropical agricultural systems. The development of technological recommendations to improve the productivity of tropical root crops in the tropics is dependent on an understanding of important underlying agroecological principles. The objective of background ecophysiological work is to develop crop-specific technological packages appropriate to low-input subsistence farming and to match specific crops with a cropping system that will result in adequate yields and in ecological and socioeconomical sustainability. Because of the close relationship between crops and humans in small-scale farms of the tropics it is imperative that agroecology research be holistic, multidisciplinary, and cognizant of the many socioeconomic and cultural factors that will determine whether improved technologies will be adopted in any given location.

When Hawaii&#x27;s farmers need a low-growing cover crop for their coffee, ornamental tree, or macadamia orchards, the USDA Plant Materials Center on Molokai often recommends the cultivar &#x27;Tropic Lalo&#x27;paspalum (Paspalum hieronymii). This non-invasive grass grows fairly ...

Annual ryegrass (Lolium multiflorum), a multipur-pose European import, is often chosen as a “living sod” cover crop in vegetable and fruit crops. Its vigorous root system tenaciously holds the soil against erosion while improving soil organic matter levels, increasing water ...

White sweetclover (Melilotus alba) is a biennial legume that can be a valuable tool for sustainable farming in the tropics. This plant produces an extensive root system and a deep taproot to scavenge soil nutrients and moisture from deep in the ground. These nutrients ...

The tomato, Lycopersicon lycopersici, is the number one vegetable crop in Hawaii in terms of popularity and market value. This unique vegetable, a member of the Solanaceae Family along with the peppers and the Irish potato, is a native of Central and South America. ...

Effective and efficient water resource management is undoubtedly one of the most important policy issues facing agriculture in Hawaii in the years ahead. Substantial amount of water could be saved through optimizing plant water uptake and minimizing excess water looses below root zones. Capacitance sensors have been successful in monitoring water content at multiple depths and at different locations in near real-time. The objectives of this work are to use real-time data from capacitance sensors to: i) determine field soil physical properties, i.e., soil hydraulic conductivities and soil water holding capacity; ii) determine irrigation scheduling setting points, i.e. full points and refill points. Six capacitance probes were used to monitor the soil water content in real-time (every 10 minutes) across the field. Each probe has four soil moisture sensors that monitor the water content at 10, 20, 30 and 50 cm below the soil surface. Soil hydraulic conductivity at 10 and 40 cm was determined across the field. Rain and irrigation were also monitored during the period of the study. Among the three investigated tomato plant varieties, Toro variety treatment had lowest water content in all investigated soil depths compared with the two other treatments. This variety seems to have higher water uptake than Ruby and Atila F1 varieties.

Summary A round and specialty eggplant variety trial was conducted at the UH Waimanalo Experiment Station. 31 varieties were grown for about 2 years, and harvested twice weekly for about 17 months, to evaluate their growth, yields, and fruit quality. Results are presented for 3-, 8-, and 17- month-yields to provide an indication of potential short-term and long-term yields for the varieties evaluated. Higher long-term yields may be an indication of the variety&#x27;s adaptability to grow at low-elevation conditions in Hawaii. Standard varieties grown in Hawaii, and used as reference varieties for this trial included Black Bell & Classic (oval types), and Waimanalo Long and Nitta x Waimanalo (standard Japanese long-types). After looking at the results and variety descriptions, some growers may chose to try growing some of the varieties that didn&#x27;t yield as well, but that have quality characteristics (color, shape, taste) sought after by specialty niche markets.

Five experiments, consisting of 3 successive plantings per experiment (for a total of 15 field trials, or 39 individual cultivar/P rate trials) were conducted over a 2 year period to evaluate the response of three mustard cabbage varieties to five rates of phosphorus fertilizer applications. The P applications ranged from 0 to 400 lbs/Acre, applied to experimental fields that according to current UH-CTAHR recommendations already had very high P levels, which would thus be expected to require no additional P applications. The trials were conducted at three different sites, representing three distinct soil types (representing Mollisols, Oxisols, and Inceptisols groups), at three elevations (70, 880, and 2200 ft asl), and were conducted during different parts of the year (including cool, warm, and hot planting seasons). Overall, out of the total number of 39 individual trials conducted, 64% showed a response to external P applications. The greatest percentage response rate to P applications occurred at the high elevation sites (100% in Lalamilo and 73% of all the trials conducted in Poamoho, compared to 45% for Waimanalo, and 8% when grown in Waimanalo during the summer months), and when the experiments were conducted during the cooler parts of the year. The three varieties evaluated showed a differential response to P, with Mizuna showing a response to P on 66% of the trials, compared to 58% for Joi Choi, and 50% for Quing Choi. Continues… Gary Kam, from NRCS-Kamuela brought to my attention in early 2001 the need to conduct P calibration studies to support the Kamuela vegetable growers. I would like to thank Gary and Dwight Sato for their initial suggestions, consulting with vegetable growers, for brainstorming ideas to set up this project, and for their help in suggesting and seeking financial support from NRCS. Ken Kaneshiro, and Larry Shinshiro, both at NRCS, also provided help to obtain research and educational grants from NRCS. We would like to thank Ray Uchida and the staff of ADSC for help with the many tissue and soil nutritional analyses conducted, and for their ongoing encouragement in support of fertilizer calibration research in Hawaii. Ted Goo did an excellent job with the extensive logistical needed to conduct relatively large sized concurrent experiments at two different sites, and with helping to maintain the integrity of the many fertilizer treatments in the rotational plots that needed to stay in place over three consecutive plantings. We would like to thank farm managers Roger Corrales, Susan Migita, and Milton Hamasaki, and their dedicated staffs at the Waimanalo, Poamoho, and Lalamilo Experiment stations for their extensive logistical and field support in helping to maintain these experiments for a period of over two years. Without their help and attention to detail in all aspects of the project, including field establishment, maintainance, scheduling operations, and extensive data collection, these trials would have not come up to fruition. We would like to thank the cooperators of this project (listed above) who helped with brainstorming to prepare the experimental design and provided suggestions throughout the duration of the project. Christine Crosby, research associate, helped with data collection and data input. Thank-you to Dave Wall for his willingness and dedication, shortly after his arrival to the Big Island, to conduct the research trials and data analysis in Lalamilo, which involved many long round trips from Hilo to Kamuela, and coordinating activities with the staff in Lalamilo. Lina Huang, student assistant, helped with data input. The NRCS-EQUIP project, NRCS, and the DOA kindly provided grants to finance this project.

What is Organic Farming? Organic farming is a form of agriculture which does not use synthetic inputs such as pesticides and fertilizers because of the disruptive effects that the synthetic chemicals can cause on the ecological balance considered essential to maintain a sustainable system indefinitely. Organic farming thus differs from other alternative ag