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- Author or Editor: Joseph DeFrank x
A modified power function, y = (A + B·x)–C, was developed for determining the relationship between plant growth and growth retardant treatment. This function accounts for the plant response characteristics by incorporating three coefficients: A, growth level of the nontreated plants; B, the degree of growth reduction; and C, the smallest effective dose of the growth inhibitor. The function accounted for 97% of the variation in purple nutsedge (Cyperus rotundus L.) leaf length as a function of the amount of a growth retardant applied. The procedure resulted in a smaller error sum of squares than several common nonlinear functions because of its greater shape flexibility.
Anthurium bacterial blight is a disease that has devastated much of the Hawaii anthurium industry in recent years. In response to the crisis, the Cooperative Extension Service produced a video entitled “Strategies for Anthurium Blight Control - A Growers' Discussion.” The video format was selected to allow the extension service to utilize experience of four successful large scale commercial growers and deliver blight control information to other growers with a graphic demonstration on control procedures for disease management. Production of the video eliminated the need for farm tours, eliminated the risk of disease spread, condensed information, and allowed growers to borrow copies. This video proved effective in prompting growers to adopt and implement recommended blight control procedures.
Abstract
Macadamia (Macadamia integrifolia, Maiden et Betche) husks, a waste product of the industry, could serve a useful purpose as a mulch (8). However, uncomposted husks have been shown to be toxic to germinating corn (Zea mays L.) seedlings when mixed with vermiculite as a potting medium. In a composting study, unamended heaps of macadamia husks retained potent phytotoxic compounds for at least 209 days (unpublished data). Observations (H. Ooka, personal communication) indicated that mature macadamia trees could be killed with high levels of fresh husks used as a mulch around the base of plants. The objective of this study was to measure the yield, growth, and leaf nutrient levels of mature macadamia trees in response to increasing amounts of uncomposted husks applied as a surface mulch.
Pejibaye (Bactris gasipaes Kunth) is being evaluated in Hawaii for production of fresh heart-of-palm. Yields and offshoot (sucker) production were evaluated in response to woven black polypropylene mat (control), three legumes [Arachis pintoi Krap. & Greg., Cassia rotundifolia Pers., and Desmodium heterocarpon (L.) DC], and a grass (Chloris gayana Kunth) used as ground covers. D. heterocarpon and C. gayana formed closed canopies quickly and controlled weeds well, but required more frequent mowing. A. pintoi formed a closed canopy slowly and only controlled weeds after forming a thick canopy, but required less mowing. Cassia rotundifolia died out after flowering and setting seed. All vegetative ground covers delayed heart-of-palm harvest and had reduced yields 1.5 years after planting. A combination of polypropylene (adjacent to plants) and vegetative ground covers (in service rows) may provide the best solution to minimizing labor for vegetative management in this orchard crop.
Pejibaye (Bactris gasipaes Kunth, Palmae) is being evaluated for production of fresh heart of palm in Hawaii. Precocity, yields, and weed control were evaluated in response to woven black polypropylene mat (control), oryzalin, oxyfluorfen, and paraquat. Control plots attained 100% of plants harvested by 26 months, followed by oxyfluorfen (97.5%), oryzalin (77.5%), and paraquat (60%). Estimated heart of palm yields (3731 plants/ha) were similar with oxyfluorfen 1.2 kg a.i./ha (707 kg·ha–1), polypropylene mat (612 kg·ha–1), oxyfluorfen 0.6 kg a.i./ha (600 kg·ha–1), and oryzalin 4.5 kg a.i./ha (478 kg·ha–1). Based on precocity, yields, and weed control efficiency, the performance rating of these weed control treatments was mat ≈ oxyfluorfen > oryzalin > paraquat. Chemical names used: 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene (oxyfluorfen); 1,1′-dimethyl-4-4′-bibyridinium ion (paraquat).
Yield components of 4 anthurium cultivars over a 2 year harvest period were determined. The varieties are `Ozaki' (red color-OZ), `Nitta' (orange-NT), `Kozohara' (dark red-KZ) and `Marian Seefurth' (pink-MS). The herbicide treatments are: diuron (1.1 kg ai/ha) every 3 months (DN); granular formulation of oxyfluorfen (2%) and oryzalin (1%) (3.4 kg ai/ha) in an alternating 3 month cycle with diuron (1.1 kg ai/ha) (OO). Black polypropylene mulch (PM) is the non-chemical control treatment. Yield components include: total cut flower yield, mean stem length and mean flower size (spathe width × length). Total flower yield was not significantly affected by weed control treatments. Yield ranking was: MS>KZ=NT>OZ. A significant interaction was recorded for stem length and flower size. OZ stem length was unaffected by weed control treatments while the others showed variations dependent on treatments. KZ and OZ flower size was not affected by weed control treatments, however, herbicide treatments did reduce flower size of MS and NT. Weed control ranking was: PM=00.>DI.
Pejibaye (Bactris gasipaes Kunth) is being evaluated in Hawaii for production of fresh heart-of-palm. Yields and offshoot (sucker) production were evaluated in response to woven black polypropylene mat (control), three legumes [Arachis pintoi Krap. & Greg., Cassia rotundifolia Pers., and Desmodium heterocarpon (L.) DC], and a grass (Chloris gayana Kunth) used as ground covers. D. heterocarpon and C. gayana formed closed canopies quickly and controlled weeds well, but required more frequent mowing. A. pintoi formed a closed canopy slowly and only controlled weeds after forming a thick canopy, but required less mowing. Cassia rotundifolia died out after flowering and setting seed. All vegetative ground covers delayed heart-of-palm harvest and had reduced yields 1.5 years after planting. A combination of polypropylene (adjacent to plants) and vegetative ground covers (in service rows) may provide the best solution to minimizing labor for vegetative management in this orchard crop.
Pejibaye (Bactris gasipaes, Palmae) is being evaluated for heart of palm production in Hawaii. Yields and weed control were evaluated in response to: oryzalin (4.5 and 9.0 kg ai/ha), oxyfluorfen (0.6 and 1.2 kg ai/ha), paraquat (1.2 and 2.4 kg ai/ha) and woven black polypropylene mat. Four open-pollinated progenies from the Benjamin Constant population of the Putumayo landrace were used as replications. Paraquat was sprayed at 50 day intervals, while the preemergence herbicides were sprayed at 90 day intervals. Harvest started at 18 months after planting out, 17 months after treatment initiation. The polypropylene mat yielded the highest percent harvest (80%), followed by Oxyfluorfen (50%), paraquat (20%), oryzalin (12.5%). There were replication (genotype) effects that suggest varying tolerance to paraquat and oryzalin. Estimated palm heart yields (3731 plants/ha), corrected for % harvest, were highest with polypropylene mat (490 kg/ha), followed by oxyfluorfen 1.2 ai (425 kg/ha) and 0.6 ai (330 kg/ha). Paraquat severely inhibited growth of the suckers that assure future harvests. The performance rating of these weed control treatments was: mat = oxyfluorfen > oryzalin > paraquat.
Living mulches offer a low-input alternative to achieve weed control while minimizing herbicide applications, decreased fertilizer leaching, insect and nematode management. and improved soil texture. A study was conducted to evaluate the effect of a Rhodes Grass (Chloris gayana cv. Katambora) living mulch on the growth and productivity of ten eggplant. Solanum melongena, cultivars grown under fertigation. The living sod was established at the Univ. Hawaii Waimanalo Experiment Station in June 1992. Soil analysis was taken before experiment initiation. Ten eggplant cultivars were transplanted on both living-mulch and control (woven-polyethelene mulch) plots on 4 March 1993. Weekly or bi-weekly harvests were conducted for six months. beginning on 19 May 1993. In addition plant height and canopy dimensions were determined on 16 April. and 10 Nov. Plant growth was monitored throughout the experiment. Soil samples were taken from the eggplant rhizosphere, hare-ground and in Rhodes grass monoculture, for nematode count determinations. Soil samples were also taken for nutrient determination after completion of the experiment. Overall yields were greater in the polyethelene mulch than in the living mulch plots. A differential response was observed on the response of cultivars to cropping system. However the most vigorous cultivars performed well in both systems. The living mulch system showed potential for nematode management in eggplant agroecosystems.