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Open access

R. J. Oshima, J. P. Bennett, and P. K. Braegelmann

Abstract

Parsley (Petroselinum crispum (Mill.) Nym. cv. Banquet) incurred leaf injury, reduced growth, and altered assimilate partitioning after exposures to 20 pphm ozone. Total plant dry weight and root dry weight were decreased 23% and 43% respectively, with little effect on leaves. The relative growth rate of fumigated plants was reduced after the initial ozone exposure but leveled off at a steady state above that of the control plants when plant dry weights reached about 4.5 g. Ozone appeared to have its greatest effect on growth during initial exposures.

Open access

L. E. Francois

Abstract

The effect of excess B on tomato (Lycopersicon esculentum Mill.) yield, fruit size, and vegetative growth was determined in large, outdoor sand cultures. Boron treatments were imposed by irrigation with culture solutions that contained 1.0, 4.0, 6.0, 8.0, 10.0, or 12.0 mg B/liter. Relative yield was reduced 3.4% with each unit increase in soil solution B (Bsw) above 5.7 mg B/liter. Market quality of the fruit was reduced significantly by increased B concentrations. The occurrence of leaf injury and reduction in vegetative growth were not reliable indicators for B tolerance.

Open access

T. Elkiey and D. P. Ormrod

Abstract

Eighteen cultivars representing 6 species (Poa pratensis L., Agrostis alba L., Agrostis palustris Huds., Agrostis tenuis Sibth., Festuca rubra Gaud., and Lolium perenne L.) of cool season turfgrass were exposed to 15 pphm ozone for 6 hours daily, 15 pphm sulfur dioxide continuously, 15 pphm nitrogen dioxide continuously, or a mixture of all three at these concentrations for 10 days. The most common symptoms of injury on sensitive cultivars in response to these gases were bleaching and necrosis of leaves with some cultivars exhibiting dark brown necrosis and stippling in response to O3 alone. Cultivars varied in sensitivity to O3 or SO2 from very sensitive to insensitive while few cultivars were sensitive to NO2 alone at the concentration used. Exposure of some cultivars resulted in less leaf area production but no visible injury symptoms, while other cultivars had leaf injury without reduction of area of uninjured leaves. The combined exposure caused more leaf injury and greater reduction in the leaf area production by most cultivars compared with plants exposed to single gases. Exposure to single pollutants could provide inaccurate estimates of turfgrass cultivar sensitivity outdoors where several pollutants may occur simultaneously.

Free access

R.E. Byers, J.A. Barden, and D.H. Carbaugh

Terbacil applied to whole-spur `Delicious' apple (Malus domestica Borkh.) trees reduced photosynthesis and fruit set. The addition of the surfactant X-77 to terbacil sprays increased fruit thinning and leaf injury. Terbacil sprays applied to leaves only (fruit covered with foil) were as effective as when applied to leaves plus fruit. Dipping fruit alone in a terbacil solution did not cause abscission. Shading trees for 4 days with 92% polypropylene shade material reduced fruit set =50%. Spraying trees with carbaryl reduced fruit set by 25%. The combination of shade + carbaryl spraying reduced fruit set by 89%. Chemical names used: l-naphthalenyl methylcarbamate (carbaryl); 3-tert- butyl-5-chloro-6-methyluracil (terbacil); 2-chloroethylphosphonic acid (ethephon); alkaryl polyoxyethylene alcohols (X-77).

Open access

L.E. Francois

Abstract

The boron tolerance of broccoli (Brassica oleracea L. Italica Group), cauliflower (Brassica oleracea L. Botrytis Group), and radish (Raphanus sativus L.) was determined in large, outdoor sand cultures. Boron treatments were imposed by irrigation with culture solutions that contained 1.0, 4.0, 8.0, 12.0, 16.0, or 20.0 mg B·liter−1 for broccoli and cauliflower, and 1.0, 3.0, 6.0, 10.0, 13.0, or 16.0 mg B·liter−1 for radish. Relative yield was reduced 1.8%, 1.9%, and 1.4% with each unit (mg·liter−1) increase in soil solution B (Bsw) above 1.0, 4.0, and 1.0 mg B·liter−1 for broccoli, cauliflower, and radish, respectively. Increasing Bsw significantly reduced plant size of all 3 vegetables. Over the B range tested, no leaf injury was apparent for these 3 vegetables.

Open access

Anton M. Kofranek and Abraham H. Halevy

Abstract

Cut flower buds of chrysanthemums were opened in sucrose solutions from 0 to 40%. Concentrations of 2% for ‘Albatross ’, 5% for ‘Fred Shoesmith’, 20% for ‘Streamer’ and 30% for ‘Bright Golden Anne’ were optimal under room conditions of 100 ft-c fluorescent light (24 hr); relative humidity, 40 to 70%; temp 19 to 21°C. Sucrose was better than glucose; manitol was toxic. Silver nitrate (25 ppm) and citric acid (75 ppm) resulted in best quality flowers without leaf injury; 200 ppm 8-hydroxyquinoline citrate caused leaf damage. Buds larger than 5.0 cm diam and 10 g fr wt were best for opening in sucrose solutions. Flowers opened in solution in 7-9 days and were better quality and had greater longevity than those opened on the plant in the greenhouse.

Open access

D. J. Papple and D. P. Ormrod

Abstract

The systemic fungicides benomyl and carboxin were evaluated in controlled environment chambers as ozone protectants on annual bluegrass (Poa annua L.), Kentucky bluegrass (Poa pratensis L. cv. Merion) and creeping bentgrass (Agrostis palustris Huds. cv. Penncross); and in open-top outdoor chambers on creeping bent-grass. Benomyl sprays were effective in reducing ozone-induced injury in controlled environments on all grasses at all rates used. Carboxin was not a satisfactory ozone protectant and had direct toxic effects on leaves of all 3 species. Growth retardation due to ozone or carboxin was generally proportional to leaf injury. Benomyl sprays in the outdoor situation limited ozone injury on creeping bentgrass for several weeks in the summer but for a much shorter time in the fall.

Free access

Donald T. Krizek and Roman M. Mirecki

Cellulose diacetate has been widely used in UV-B enhancement studies under field and controlled-environment conditions since the early 1970s to remove wavelengths below ≈290 nm, without any evidence of toxicity effects. However, while conducting UV-B exclusion studies in window boxes covered with cellulose diacetate (CA) or in Plexiglas chambers lined with CA, there was marginal chlorosis and cotyledon epinasty in `Ashley' cucumber, which is normally resistant to elevated UV-B, while seedlings exposed to open sunlight and those grown under polyester (PE) film to exclude UV-B were free of visible injury. These findings suggested that the CA filter itself may be causing toxicity. To test this hypothesis, a UV exclusion study was conducted in which CA or Teflon (T), both UV-B and UV-A transmitting films, were used to cover window boxes in the following four combinations (top/bottom): CA/CA, CA/T,T/CA, and T/T. When CA was used as the bottom filter (CA/CA and T/CA), the plants showed significantly greater leaf injury and a 2- to 3-fold reduction in growth than when T was used as the bottom filter (CA/T and T/T). These findings suggest that toxicity is caused by CA itself rather than by solar UV-B radiation, possibly as a result of outgassing of phthalates known to be used as plasticizers in the manufacture of CA. Further evidence that CA was responsible for leaf injury was provided by a companion study in which T was replaced by PE and damage was still observed, although no significant growth effects of CA position were observed.

Free access

J. Thomas Raese and S. R. Drake

Sprays of calcium materials were applied at high volume rates (620 g Ca/400 liters) with a handgun during early June, late June, and mid-July versus mid-July, early August, and late August for five years, 1985 to 1989. Leaf injury was most severe for the late sprays but no spray injury was observed on the fruit surfaces. Bitter pit was markedly reduced with all sprays except CaSO4. In some years, bitter pit was controlled better with the early sprays. Either early or late sprays improved fruit quality including overall appearance, reduced scald development, improved red color of the skin, increased fruit firmness and reduced incidence of bitter pit in cold air (0°C) storage. Soluble solids and acidity in the fruit was not affected by calcium sprays. Leaf Ca was higher from the late spray applications than from the earlier applications. All calcium chloride spray materials resulted in increased fruit peel and cortex Ca. Calcium nitrate sprays tended to increase fruit nitrogen concentrations leading to undesirable higher N:Ca ratios in the fruit.

Free access

J. Scott Cameron, Carol A. Hartley, Carl H. Shanks Jr., and Jeannie K. L. Garth

At two-week intervals from 17 June to 15 July, three groups of `Meeker' red raspberry plants were infested with two-spotted spider mites (Tetranychus urticae) in a greenhouse. While populations on individual plants were allowed to develop freely, control plants were kept free of mites with a chemical miticide. Gas exchange measurements were made on 27 July prior to visible mite damage, and on 7 October after injury was apparent. The relationships between mite populations and leaf gas exchange and chlorophyll characteristics were described using a logarithmic function.

Physiological responses to mite feeding were observed prior to visible leaf injury. On both dates, CO2 assimilation rates decreased (p ≤ 0.001) with increasing mite numbers per leaflet. On 27 June, a significant relationship (R2 = 0.61***) was found between mite number and mesophyll conductance (gm). On 7 October, significant relationships (p ≤ 0.001) were also observed with gm, stomatal conductance (gs), and transpiration (E). Total chlorophyll content of leaves decreased with increasing mite populations, but chlorophyll a/b ratio and dry weight per leaf unit area were unchanged.