Abstract
Phytotoxicity of burlap treated with 6 concentrations of CuSO4 or copper naphthenate (Cu Nap) was determined by enclosing the root balls of Cotoneaster divaricata in the treated burlaps, observing their growth for 40 weeks, and analyzing root, stem and leaf tissue for Cu, Fe, and Mn. Burlap treated with up to 4.0% Cu Nap or levels of CuSO4 less than 0.2% was not phytotoxic. Burlap treated with solutions of CuSO4 ≥0.2% was phytotoxic. Tissue analyses indicate that the injury from CuSO4 treated burlap was the result of high Cu concentrations in the roots of enclosed plants.
Pesticides are used extensively in ornamental production. Studies of repeated pesticide applications indicate that microbial changes occur in the rhizosphere of the plant. In addition to controlling the target pest, often a population shift of bacteria may occur. This has been previously shown in research associated with leatherleaf fern [Rumohra adiantiformis (Forst.) Ching] and the fungicide benomyl. Rhizobacteria (root-associated bacteria) of anthurium (Anthurium andraeanum) were investigated with respect to total populations and isolates that are potentially phytotoxic. The anthurium sample roots were taken from commercial Jamaican production sites. The sites had either a benomyl or non-benomyl history. Rhizobacterial populations were estimated by dilution plating and subcultures were taken for a phytotoxicity bioassay. Micrographs of samples were prepared to examine treatment effects on the morphology of roots. Rhizobacteria populations were frequently at 106 colony forming units per gram fresh weight. Consistently, greater than 50% of the isolates from each treatment were potentially phytotoxic. However, in the benomyl history samples, there was a greater diversity of phytotoxic isolates.
The objective of our experiment was to determine if the application of two deer repellents to six grape cultivars (Vitis vinifera L.) caused significant phytotoxic effects, production losses, or altered the sensory characteristics of wine. We evaluated fifteen single vine plants from six different cultivars in a randomized block design that included the two repellent treatments and an untreated control. During spring 1997, we applied repellents biweekly from budbreak until flowering (2 Apr. to 14 May). Plantskyyd was applied more frequently than recommended by the product label (for trees) due to rapid emergence of unprotected shoot growth in vineyards. Hot Sauce and Plantskydd caused some initial minor phytotoxicity during 1997, however, the yield and phytotoxicity of treated plants were similar to controls by harvest. A panel detected a significant difference in the color, aroma, or taste of `Chardonnay' wine made from grapes treated with repellents compared to wine made from untreated control grapes (P = 0.001 for Hot Sauce; P = 0.05 for Plantskydd). We conclude that Hot Sauce and Plantskydd did not cause serious production losses or phytotoxic effects for the six cultivars treated. However, both Hot Sauce and Plantskydd significantly altered the sensory attributes of Chardonnay wine, which may preclude the use of chemical repellents in wine grape vineyards under the experimental conditions applied in our study.
Abstract
Over a 6-year period (1969-1974) the efficacy of 3 insecticides and 24 herbicides and their interactions in combination were investigated when applied to field-seeded broccoli (Brassica oleracea L. Italica group), cabbage (Capitata group) and cauliflower (Botrytis group). Of these, broccoli was the most susceptible to injury. Of 212 herbicide-insecticide combinations, 26 caused phytotoxic symptoms in broccoli, 20 in cabbage and 8 in cauliflower. The insecticides, thionazin, fensulfothion and carbofuran, were each involved in 1 or more phytotoxic combinations in each of the 3 crops. Ten herbicides were involved in phytotoxic reactions: alachlor, aziprotryn, benefin, CDEC, chlorpropham, cycloate, prometryne, propachlor, prynachlor and PP493. Root maggot damage was reduced markedly by the insecticides. Carbofuran allowed less damage than either fensulfothion or thionazin. None of the herbicides showed any insecticidal properties, and some decreased the effectiveness of the insecticides.
Phytotoxicity from hydrogen cyanide (HCN) fumigation was measured in several varieties of Hawaiian cut flowers and foliage (Zingiberaceae, Heliconia, Orchidaceae, Marantaceae, Lycopodiaceae, Agavaceae, Proteaceae) as a potential disinfestation treatment. Concentrations tested were 2500, 3700, 4600, and 5500 ppm HCN for 30 min. All foliage and most heliconia were undamaged at fumigation levels of 5500 ppm HCN; most protea and `Midori' anthuriums were uninjured at 4600 pm HCN; red and pink ginger were uninjured at 3700 ppm HCN; and all pincushion protea showed phytotoxicity to HCN. Red ginger was quickly damaged when exposed to sunlight immediately after treatment at 2500 ppm HCN. No injury was observed in simulated shipment tests of red ginger and `Ozaki' anthuriums fumigated at 2500 ppm HCN. Wet, red ginger flowers longer than 6 cm were damaged at 2500 ppm HCN, whereas shorter flowers were uninjured. Wet `Ozaki' anthuriums showed phytotoxicity only at 4600 ppm HCN. Wet, treated lycopodium and bamboo orchid foliage was not injured. The number of marketable days and shelf life of the treated plant material were estimated from the visual ratings.
Abstract
The tumid spider mite (Tetranyehus tumidus banks) is the most common and destructive spider mite species on palms in nursery and landscape plantings. Treatments with two applications of aldicarb, dienochlor, Tricychohexyltin hydroxide (Dowco-213), propargite, oxythioquinox, and hexakis (beta, beta-dimethylphenethyl)-distannoxane, (SD-14114), left less than 1 mite per 3 leaflet sample on container-grown parlor palms (Chamaedorea elegans Mart.). This degree of control was also obtained but with phytotoxicity by chlordimeform, 0-[5-chloro-1-(methylethyl)-1H-1,2,4-triazol-3-yl] 0,0-diethyl phosphorothioate (CGA-12223), oxamyl, and S-tricyclohexyltin 0, 0-diisopropyl phosphorodithioate (R-28627). Other miticides which caused significant population reduction and no phytotoxicity were acephate and tetradifon. Treatments of chlorobenzilate, dicofol, and formetanate reduced populations significantly but resulted in plant damage.
The repellency and toxicity of a petroleum-based proprietary horticultural oil, Sunspray 6E Plus, was tested against the greenhouse whitefly, Trialeurodes vapor-ariorum (Westwood), on greenhouse-grown chrysanthemums [Dendranthema ×grandiflorum (Ramat.) Kitamura cv. Iceberg]. A 2% (v/v) aqueous spray repelled adult whiteflies for at least 11 days after spraying and it was toxic to newly hatched and third stage larval whiteflies. No phytotoxicity was observed when four weekly sprays of 1%, 2%, and 4% oil were applied.
Five preemergence herbicides were applied to seven herbaceous perennials to evaluate weed control efficacy and phytotoxicity. Different species were used each year. The species used during 1992 were coneflower (Rudbeckia fulgida Ait. `Goldstrum'), common foxglove (Digitalis purpurea L. `Excelsior'), Shasta daisy (Leucanthemum ×superbum Bergmans `Alaska'), Stokes's aster (Stokesia laevis Greene `Blue Danube'), and avens (Geum Quellyon Sweet `Mrs. Bradshaw'). The species used in 1993 were woolly yarrow (Achillea tomentosa L.) and woolly thyme (Thymus pseudolanuginosus Ronn.). The herbicides and rates were napropamide (Devrinol 10G) at 4 and 8 lb a.i./acre; metolachlor (Pennant 5G) at 4 and 8 lb a.i./acre; oxyfluorfen+oryzalin (Rout 3G) at 3 and 12 lb a.i./acre; trifluralin (Treflan 5G) at 4 and 8 lb a.i./acre; and oxadiazon (Ronstar 2G) at 4 and 8 lb a.i./acre. Plants were grown in no. 1 containers and weed seeds were sown onto the substrate surface. Two control treatments, no herbicides but with weeds (weedy control), and no weeds or herbicides (weed-free control) also were evaluated. Weed control was effective and similar for all herbicides tested. Napropamide at 8 lb a.i./acre caused stunting in foxglove (20% to 45% less growth compared to weed-free control). Oxyfluorfen + oryzlain at 12 lb a.i./acre caused severe phytotoxicity (≈80% to 95% of plant injured) and stunted the growth (70% to 80% less growth, sometimes plant death) of woolly yarrow. Woolly thyme was stunted by all herbicides when applied at the recommended rates (42% to 97% less growth compared to control) except for oxadiazon and oxyfluorfen + oryzlain. Woolly thyme appeared to be more susceptible to phytotoxicity due to its less-vigorous growth habit and shallow, adventitious roots that were in contact with the herbicide.
Postemergence control of Phyllanthus urinaria L. (chamberbitter) in nursery and landscape plantings has been primarily limited to hand-weeding. Prodiamine was evaluated for postemergence control of chamberbitter and phytotoxicity to containerized ornamentals. On 20 June 1995, prodiamine at 0, 1.68, 3.36, or 6.72 kg a.i./ha was applied over-the-top to immature chamberbitter growing in 3.8-L containers of established Buddleia davidii Franch. `White Bouquet' Cuphea hyssopifolia HBK. `Desert Snow', Lantana camara L. `Irene', and Lantana montevidensis (Spreng.) Briq. `Lavender Weeping'. Weed-free checks were included. Applications were made with a compressed air backpack sprayer. There were four replications per treatment placed in a randomized complete block design by species. Plants were established and maintained on a container bed under full sun and overhead irrigation. Growth of and phytotoxicity to the ornamentals species, and percent coverage and number of chamberbitter, were recorded periodically for 14 weeks after treatment (WAT). Chamberbitter shoots were harvested for dry weight analysis 14 WAT. Prodiamine provided some postemergence control of chamberbitter. However, Cuphea and both Lantana species exhibited leaf distortion and/or delayed flowering.
At present, pitahaya (Hylocereus undatus Britt and Rose), a nonconventional crop and cactus native from Mexico, is considered very promising because of its high adaptability and tolerance to extreme agricultural conditions of tropical regions (poor soils, drought, and elevated temperatures), where they are cultivated. In addition, pitahaya fruit is well-accepted and identified as a nutraceutical food that lowers cholesterol and glucose levels in blood and might prevent stomach and colon cancers. However, little or no scientific information on chemical control alternatives of weeds in pitahaya commercial plantings have been generated. In this work, the phytotoxicity degree of seven commercial herbicides (metribuzin, glyphosate, glyphosate trimesium, paraqut, paraquat+diuron, atrazine, and halosulfuron methyl) in pitahaya plants grown under plant nursery conditions was assessed. A completely randomized design with 12 replications was used. The experimental unit was a flowerpot with a 5-month-old plants. The phytotoxicity degree was evaluated at 3, 7, 14, and 21 days after application using the scale proposed by EWRS. The herbicides that caused injury to the plants were paraqua+diuron (79%) and paraquat (77%), respectively. Metribuzin, halosulfuron-methyl, and atrazine did not cause any injury to the plants.