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- Author or Editor: Walter A. Skroch x
Abstract
The effects of five herbicides, simazine, terbacil, DP 733, trifluralin and dichlobenil were studied at two or three rates and three methods of placement around young apple and peach trees. Golden Delicious apple seedlings exhibited a greater inherent tolerance to the herbicides than June budded Candor peaches. Simazine, terbacil, and DP 733 significantly reduced the growth of both apples and peaches at all levels. Trifluralin and dichlobenil were toxic only when high rates were mixed in the soil around the tree root systems.
Abstract
A publication containing 32 pages with over 240 full colored plates was developed by the North Carolina State University Weed Science Faculty over a period of 3 years. The group was convinced that there was a strong need for this type publication in North Carolina but needed only 2,500 copies. To publish a bulletin of this caliber for our state alone would cost about $13,000 or over $5 per copy.
Abstract
During the Aprtl–October season, leaves of 7-year-old peach [Prunus persica (L.) Batsch cv. Norman] were serially dipped in a N-(phosphonomethyl)glycine (giyphosate) solution (10,000 ppm or 20,000 ppm) each month over a 2-year period. Fewer trees died the following year when giyphosate was applied as a leaf dip before July 1 than when applications were made after July 1; all applications resulted in tree injury.
Abstract
One of the authors (Skroch) has been asking himself since the early years of a long-term study initiated in 1966 (77) “What is a weed to a tree?” Apple trees in the mowed grass check plots grew less than in plots with woody vines. In another test comparing mowed sod, contact herbicide, and residual plus contact herbicide, trees having an herbicide program yielded 400 bushels/acre more fruit in the 5th year than those without. Apples in another orchard were of higher grade in plots with over 50% trailing blackberry (Rubus sp.) and poison ivy (Rhus radicans L.) ground covers than those from an area with a mowed-lawn appearance. The practice of frequent mowing, which increased grass covers in the 1960s, may have been a factor in the small fruit problem of the 1970s.
Abstract
Dormant budded plants of ‘Gloria’ azaleas (Rhododendron obtusum, Planch) and ‘Merritt Supreme’ hydrangeas [Hydrangea macrophylla (Thunb.) Ser.], and vegetative summer stock of ‘Gloria’ azaleas, were treated with various rates of chlorimuron, imazaquin, oxyfluorfen, and chloramben. Chlorimuron minimally injured both greenhouse crop species, but 0.14 kg a.i./ha was necessary to provide >70% preemergence control of the broadleaf weed species in peat-based or bark-based soilless media. Large crabgrass [Digitaria sanquinalis (L.) Scop.], redroot pigweed (Amaranthus retroflexus L.), Pennsylvania bittercress (Cardamine pensylvanica Muhl. ex. Willd.), common chickweed [Stellaria media (L.) Vill.], yellow woodsorrel (Oxalis stricta L.), and creeping woodsorrel (Oxalis corniculata L.) were the weed species tested. Imazaquin provided excellent control of all weed species at 0.56 kg a.i./ha for 14 weeks, but was phytotoxic to vegetative azaleas in both growing media. No difference in damage was detected when applications were made immediately after repotting and pinching or after 1 month of growth. Oxyfluorfen provided excellent control of all weed species for 4 weeks at 2.2 kg a.i./ha and, on all species except chickweed, for 14 weeks at 4.5 kg a.i./ha with no phytotoxicity to azaleas or hydrangeas for media drench applications. Chloramben drench and foliar spray applications at 6.7 kg a.i./ha injured vegetative azaleas regardless of application time. Foliar and drench applications of chloramben at 3.4 kg a.i./ha produced slight to moderate injury on vegetative azaleas. More injury resulted when applications were delayed until 4 weeks after pinching. Chloramben was not toxic to either dormant-budded species. Chemical names used: 2-((4[4-chloro-6-methoxypyrimidine-2yl)amino carbonvl]amino sulfonyl))benzoic acid, ethyl ester (chlorimuron); 2-[4,5-dihydro-4-methyl-4-(1-methyl-ethyl)-5-oxo-1H-imidazol-2yl]-3-quinolinecarboxylic acid (imazaquin); (2-chIoro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifIuoromethyl) benzene (oxyfluorfen); 3-amino-2,5-dichloro-benzoic acid (chloramben).
Abstract
‘Rachel’ and ‘Jan Cochran’ are Carla hybrid azaleas released in 1988 by the North Carolina Agricultural Research Service. Cold hardiness; later-blooming, semidouble, floriferous flowers; and moderate resistance to root rot were the objectives leading to selection and increase of ‘Rachel’. Cold hardiness, later-blooming floriferous flowers, moderate resistance to root rot and the unique, compact growth form resembling an English boxwood were the objectives leading to selection and increase of ‘Jan Cochran’. Stock plants have been made available to commercial nursery growers for propagation and distribution in the nursery industry.
A field study was initiated in 1981 in western North Carolina to determine the influence of eight groundcover management systems on quality of `Redchief Red Delicious' apple (Malus domestica) grafted onto rootstock of M VIIA. Management systems included: bare soil, Secale cereale mulch, minimal cultivation, Festuca arundinacea, Dactylis glomerata, Poa pratensis, Muhlenbergia schreberi and Rubus sp. Thus far, fruit quality data indicate that fruits produced in plots of cool-season grasses are smaller and less mature than those produced in vegetation-free plots or plots of warm-season grasses. A negative correlation was noted between high fruit quality and water deficit stress as measured by water potential and stomatal conductance.
A field study was initiated in 1981 in western North Carolina to determine the influence of eight groundcover management systems on quality of `Redchief Red Delicious' apple (Malus domestica) grafted onto rootstock of M VIIA. Management systems included: bare soil, Secale cereale mulch, minimal cultivation, Festuca arundinacea, Dactylis glomerata, Poa pratensis, Muhlenbergia schreberi and Rubus sp. Thus far, fruit quality data indicate that fruits produced in plots of cool-season grasses are smaller and less mature than those produced in vegetation-free plots or plots of warm-season grasses. A negative correlation was noted between high fruit quality and water deficit stress as measured by water potential and stomatal conductance.
Fraser fir [Abies fraseri (Pursh) Poir.] and Norway spruce [Picea abies (L.) Karst.] were grown in seven vegetation management programs ranging from 100% cover of grass-dominated vegetation to bare soil on opposing north and south aspects. Concentrations of 13 nutrients were determined at three growth stages during 2 years: active terminal growth, cessation of terminal expansion, and dormancy. Aspect did not affect nutrient concentrations. Vegetation management programs bad a significant impact on nutrient concentration for both species. Nitrogen, Ca, B, Fe, and Mn concentrations during dormancy were negatively correlated with herbaceous biomass. In contrast, N during active growth and P and Mg concentrations during all stages were positively correlated with herbaceous biomass. Vegetation management only affected the seasonal trend of Mo. Seasonal trends varied by nutrient in both species.