Selected herbicides were evaluated for control of southern yellow wood sorrel (Oxalis dillenii Jacq.) in three experiments. Control varied depending on rate of application and the time interval after application. Herbicides providing excellent control (less than one weed/pot) 8 weeks after treatment with the 0.5 × rate included: oxyfluorfen, 1.1 kg·ha–1; oryzalin, 2.2 kg·ha–1; and oxyfluorfen + oryzalin, 1.7 kg·ha–1. Control 18 weeks after treatment was excellent at the 1× rate with oryzalin (4.5 kg·ha–1) and at the 2× rates with oryzalin (9.0 kg·ha–1), oxyfluorfen (4.5 kg·ha–1), and a combination of the two. Chemical names used: 2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene (oxyfluorfen); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin).
Improved water use efficiency exists for plants grown in modified containers to minimize leaching and reduce irrigation frequency which subsequently reduces NO3-N leachate. Salvia splendens `Bonfire' and Impatiens wallerana `Pink' (super elfin hybrid) were potted in ProMix BX medium (Premier Brands, Inc., Stamford, CT) into nine container styles with modified drainage holes to determine leachate volume and quantify NO3-N leached. Three styles had four drainage holes on the container side with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; three styles had four drainage holes on the container side and one drainage hole in the bottom center with hole diameters of 0.5, 1.0, and 1.9 cm, respectively; and three styles had one drainage hole in the bottom center with hole diameters of 0.5, 1.6, and 1.9 cm, respectively. Plants were hand watered when an individual container's medium reached 80% of container capacity. Leachate volume, irrigation frequency, and leachate NO3-N was reduced as drainage size hole decreased in size and number. Plant quality was similar among container modifications.
Phytotoxicity associated with application of 0.28 kg·ha−1 a.i. of the 4E formulation of fluazifop-butyl to Rhododendron ‘Hino-crimson’ was characterized by plant response similar to the response to chemical pinching. Flowering the following spring increased with fluazifop-butyl treatment. In a separate study, application of 1E PP005 (a formulation containing only the active isomer fluazifop-butyl) produced effects similar to the 4E formulation at one-half the rate (0.14 kg·ha−1). Chemical name used: butyl (±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-butyl).
Our research has previously shown that soybean oil can substitute for petroleum oil for controlling insects on fruit trees. Soybean oil may also be a safe, environmentally friendly pesticide to use on nursery stock. The objectives of these experiments were to evaluate phytotoxicity of soybean oil to nursery stock and efficacy for mite control. Four replications of container-grown plants of `Alberta' spruce, `Emerald' arborvitae, `Leyland' cypress, Canadian hemlock, and `Andorra' juniper were sprayed on 26 Mar. with 0%, 1.0%, 2.0%, or 3.0% soybean oil; or 2.0% petroleum oil. None of the oil treatments caused phytotoxicity. The same plants were sprayed on 1 Aug. with 0%, 1.0%, 2.0%, or 3.0% soybean oil. Application of 1% or 2% soybean oil appeared to be non-phytotoxic to spruce, but 3% soybean oil caused slight terminal necrosis. Arborvitae, cypress, hemlock, and juniper were not injured by spraying 1% to 3% soybean oil in the summer. Container-grown burning bush plants with mite infestations were sprayed on 20 Sept. with 0%, 1.0%, 2.0%, or 3.0% soybean oil; or with 1.0% SunSpray petroleum oil. Container-grown mite-infested `Andorra' juniper plants received the same treatments, except for the 3% soybean oil. Application of 1% or 2% soybean oil to burning bush or to juniper shrubs resulted in >97% and 87% control of mites 7 and 14 days, respectively, after treatment.
Potential exists for reduced water use and improved water quality in container nurseries through redesign of the container to minimize leaching. `Celebrate' poinsettias were grown in trade gallon containers with modified drainage hole number and size. Irrigation was applied when an individual container's medium decreased to 80% of container capacity; a gravimetric method was used to determine daily water requirements. Containers with one drainage hole in the center bottom reduced applied water (13%) and leachate volume (90%) compared to standard nursery containers (4 drainage holes in the side and one in the center bottom). Plant quality was similar with these treatments.
Preemergence herbicides were evaluated for control of yerba-de-tago [Eclipta alba (L.) Hasskarl] and for phytotoxicity to four container-grown landscape species. Herbicides providing excellent control (less than one weed/pot) were chlorimuron at 0.035 and 0.07 kg·ha-1, chlorimuron + metribuzin at 0.075 + 0.485 kg·ha-1, and oryzalin at 4.5 and 9.0 kg·ha-1. Injury within 30 days after treatment occurred with applications of oxyfluorfen, lactofen, and fomesafen at the × 1 and × 2 rates on Ilex vomitoria Ait. ‘Nana’ (dwarf yaupon), Rhododendron satsuki ‘Pink Gumpo’ (‘Pink Gumpo’ azalea), R. obtusum (Lindl.) Planch. ‘Coral Bells’ (‘Coral Bells’ azalea), and Liriope muscari L. ‘Big Blue’ (lily turf). Injury symptoms were not present after 60 days, except with applications of lactofen at 0.44 kg·ha-1 and fomesafen at 1.1 kg·ha-1. All other herbicides were safe on the four ornamental species. Chemical names used: 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); N,N-diethyl-2-(l-naphthaIenyloxy)propanamide (napropamide); 3-[2,4-dich-loro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene (oxyfluorfen); N-(l-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin); 6-chloro-N,N-diethyl-1,3,5-triazine-2,4-diamine (simazine); 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide (oryzalin); methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate (bifenox); 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide (alachlor); 2-[[[[4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoic acid (chlorimuron); 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one (metribuzin); (±)-2-ethoxy-l-methyl-2-oxoethyl 5-[2-chloro-4-(trifluoromethyl)phenoxyl]-2-nitrobenzoate (lactofen); and 5-[2-chloro-4-(trifluoromethyl)phenoxyl]-N-(methysulfonyl)-2-nitrobenzamide (fomesafen).
Research was conducted to compare non-ionic, paraffin-based crop oil, soybean oil, sunflower oil, and organosilicone surfactants combined with Manage (MON 12051, holosulfuron) applied at a reduced rate for yellow nutsedge (Cyperus esculentus) control efficiency and evaluation of phytotoxicity to five container-grown ornamental species. Manage at 0.018 kg a.i./ha was combined with 0.25% or 0.5% (v/v) of the following surfactants: X-77, Scoil, Action “99”, Sun It II, or Agri-Dex. Yellow nutsedge tubers (10 per 3.8-L container) were planted into containers along with the following nursery crops: `Lynnwood Gold' forsythia, `Big Blue' liriope, `Pink Lady' weigela, `Blue Girl' Chinese holly, and `Bennett's Compacta' Japanese holly. Treatments were applied 5 weeks after potting on 13 June 1998 and phytotoxicity ratings taken 4 and 8 weeks later and growth measured after 8 weeks. Sun It II provided the most-effective nutsedge control without reducing growth and causing minimal phytotoxicity to the ornamental plants tested. X-77 (the recommended surfactant for Manage) provided only moderate nutsedge control. Efficient nutsedge control can be accomplished with Manage at one-half the recommended rate when combined with the correct surfactant. Some temporary phytotoxicity symptoms can be expected and a slight overall growth reduction is possible, depending on the surfactant selected.
Water samples containing 0, 2.5, 10.0, or 20.0 ppm nitrate and ammonia were evaluated under 3 temperatures (0, 6, 20C) plus or minus sulfuric acid (36N) for changes in concentration. Ammonia and nitrate levels were measured 0, 1, 2, 4, 8, 16, 24, and 32 weeks after storing. Response to storage conditions was the same regardless of acid or concentration of ammonia or nitrate. Nitrate concentrations in the storage locations were similar for the first 2 weeks. Afterwards, treatments stored at room temperature fluctuated from initial standards. With ammonia, frozen samples had the greatest deviation from initial standards during the first 4 weeks. By week 24, ammonia samples stored at room temperature had exceeded acceptable deviations from the standards. Nitrate and ammonia samples held in refrigeration had the least fluctuation during the 32 week storage period.
The effects of overhead pulse irrigation versus conventional overhead irrigation on growth of Ageratumhoustonianum `Blue Puff' in 2 media, container leachate volumes and leachate NO3-N and NH4-N levels were evaluated. Container leachate volumes, and NO3-N and NH4-N levels were higher with pinebark:sand medium. Container leachate volumes tended to be lower with pulse irrigation compared to conventional irrigation. Shoot dry weights of plants grown in pinebark:peat were greater under conventional irrigation compared to pulse irrigation; however, growth indices, flower number, and NO3-N and NH4-N levels were not affected by irrigation method in either medium.
Fully expanded apical leaves of Ipomoea batatas (L.) Lam. cv. Jewel were exposed three times during the day to a square wave of 11CO2 for sufficient duration to approach steady-state isotope equilibrium in the plant. This procedure allowed monitoring of changes in the storage of photosynthate within the treated leaf and the transport and allocation of this carbon throughout the plant during the day. Early in the day, export of photosynthate from the treated leaf predominated over storage (57:43%). By mid-day, export had declined to a point that storage was favored (44:56%). Toward late afternoon, export again increased (54:46%). These changes in the allocation of carbon within the leaf were reflected by alterations in the size and turn-over time of the export pool of photosynthates within the labeled leaf. The latter increased progressively from early morning (19 min) until late afternoon (27 min). The speed of photosynthate transport within the plant varied with position along the main stem. Speeds up to 6 cm·min−1 were found between short segments of the stem (i.e. ≈10 cm). As the distance between sites increased, slow and fast rates were averaged, giving mean speeds of 2.0 to 2.5 cm·min−1. The speed of transport also changed during the day and depended, in part, on the position of the transport path along the main stem. Virtually no carbon was translocated acropetally from labeled fully expanded apical leaves during the day. Although some photosynthate was translocated into lateral branches developing at the base of the plant, the predominate sink was the root system.