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A survey of hazelnut (Corylus avellana L.) genotypes for response to the eastern filbert blight pathogen [Anisogramma anomala (Peck) E. Müller] was performed. Seven varieties were discovered that did not display disease signs or symptoms when subjected to severe inoculation with A. anomala in the greenhouse and assayed for infection. These cultivars are `Closca Molla', `Ratoli', `Yoder #5', `Potomac', `Medium Long', `Grand Traverse' and `Zimmerman'. `Ratoli' and `Closca Molla', both minor varieties from Spain, are superior agronomic types to the resistant cultivar Gasaway, which has been the main resistance source used in the breeding program. Only `Zimmerman' carries the RAPD marker linked to resistance in populations segregating for the `Gasaway' gene. Three populations were created using, `Zimmerman', as the pollen parent in controlled crosses. These populations were inoculated with spores of the pathogen and assayed by indirect ELISA and by observation of canker incidence. Resistant phenotypes make up 84% of the populations, indicating that `Zimmerman' possesses resistance either distinct from or additional to that found in, `Gasaway'. A RAPD marker linked to the resistance gene in crosses with `Gasaway' cosegregates with the resistant phenotype in all three populations (0 cM, 3 cM, 4 cM). Mechanisms to explain the distortion in these populations are discussed. Further studies are required to characterize the mechanism and inheritance resistance in these other clones.

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Excessive moisture is a problem in evaluating recycled paper products as mulch to replace other common mulch materials and in landscape and container uses. To isolate the water associated with soil and/or media, two recycled paper products, pellets or crumble, were used as mulches in trade gallon containers in a greenhouse. Pine bark, pellets, and crumble needed to obtain standard mulch depth were enclosed in plastic mesh. These mulches were placed in containers that contained 1 kg of a 7 pine bark : 1 sand media. All containers were saturated with tap water for 24 hours. Mulches were placed on each container and allowed to drain for 1 hour. Weights of media, mulch, and media and mulch were obtained every 24 hours for a total of 312 hours. Water content of the media was not influenced by any of the mulch treatments. Water content of the paper products was increased by a factor of two. Pine bark mulch water content was zero 96 hours after an initial dry down cycle began, while the water content of pellet and crumble were 100 and 90 cm of water. Total water content of the media plus the mulch was increased by 30% to 35% when compared to pine bark mulch alone. However, the increase was associated with the water content of the waste paper mulch.

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Abstract

Environmental concerns and disadvantages of synthetic insecticides have stimulated interest in natural chemicals derived from plants for insect control. Extracts from seeds of the neem tree (Azidirachta indica A. Juss) have attracted attention as an insecticide not only because of its broad spectrum action, but also because it has demonstrated uncommon safety to man and warm-blooded animals and the environment (Henkes, 1986). Furthermore, neem extract has been reported to act systemically to effectively control serpentine leafminer (Liromyza trifolii Burgess), a serious pest on ornamentals and vegetables due mainly to pesticide resistance (Larew et al., 1984; Lindquist et al., 1986; Stein and Parrella, 1985; Webb et al., 1983). Larew et al. (1984) demonstrated that neem soil drenches provided systemic control of L. trifolii for up to 3 weeks. Lindquist et al. (1986) investigated the use of neem insecticide (Margosan-O) as a preshipping crop treatment by soaking bare root cuttings in neem solutions. Their 2- to 4-hr soaks (3.0% Margosan-O) effectively controlled leafminers for 4 weeks. The objective of this study was to determine if a simple in-transit application method could provide control of serpentine leafminers on chrysanthemum.

Open Access

Two studies were conducted to evaluate recycled newspaper mulch for landscape plantings. In the first study, two paper products (pellets and crumble) were tested at three depths. Application of either 25 or 50 mm provided excellent control of prostrate spurge. Of the four annuals grown, ageratum exhibited severe stunting of roots and shoots. In the second study, three annual species were mulched with the two recycled paper products applied at 25 mm each and adjusted with P at 0, 3.75, or 7.5 ppm to bind excess Al. When no P was added, ageratum growth was about half that of the control plants. Addition of P at either rate resulted in similar growth compared to control plants. Marigold and geranium were less affected by recycled paper mulch; however, when P was added growth was always similar to nonmulched control plants.

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The effects of fertilizer placement on growth and nutrient uptake of `Count II' tomatoes (Lycopersicon esculentum Mill.) were evaluated in a 3-year study. Fertilizer was applied broadcast at two rates or banded in two bands at two widths or in four bands, or applied in combinations of sidedressing or broadcasting with banding of N, P, and K at 56, 112, or 224 kg·ha-1 each. Total fruit yield for the 112 kg·ha-1 banded treatment was 24% higher than that for the same rate broadcast and similar to yield for 224 kg·ha-1 broadcast. Treatments involving combined placements, wider bands, or four bands produced yields similar to that for 112 kg·ha-1 banded, but the 56 kg·ha-1 banded with two 56 kg·ha-1 sidedressings had the highest yield. Leaf concentrations and plant contents of N, P, and K and percentage recovery of quantities applied were generally higher in treatments involving banding or sidedressing when compared to broadcasting. Leaf Mn was much higher in banded or sidedressed than for broadcast treatments but was lower when 112 kg·ha-1 was applied in four bands than in two. Only with Mg and Mn were leaf concentrations and plant contents highly correlated. With 112 kg·ha-1 banded, 31.2% of the N, 5.8% of the P, and 44.7% of the K applied were taken up, compared to 12.5%, 2.3%, and 17.2%, respectively, for double this rate broadcast.

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Abstract

Several lots of lettuce seed were separated into fractions varying in seed width and weight per seed. Seed vigor, as measured by the slant test, was found to vary in relation to seed weight. In field trials low vigor seeds emerged slower with less total emergence and produced smaller seedlings at thinning time than high vigor seeds. Head size at harvest and percent marketable heads were greater from high vigor seeds. It is suggested that seed vigor can be used to evaluate potential field performance of lettuce.

Open Access

Resistant cultivars are a promising disease control method for eastern filbert blight, which is devastating hazelnut production in Oregon. In 1990, two studies were begun to evaluate the relative resistance of European hazelnut (Coyhls avellana) genotypes to the causal fungus, Anisogramma anomala. A randomized block design of 40 genotypes was planted using inoculated trees planted in the borders as the disease source. The first- and second-year disease incidence (percent) were compared to the published disease incidence (percent) based on exposing potted trees of 44 genotypes to high doses of inoculum. Disease incidence was significantly correlated between the two studies in 1991 (r =0.41, P = 0.02) and in 1992 (r =0.64, P = 0.001; rs = 0.35, 0.025 < P < 0.050). Three genotypes, however, showed no disease in the field, but they had disease in >70% of the potted tree study. A plot of disease incidence in the field planting indicates that the inoculum was present throughout the blocks.

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Sap nitrate was determined with the ion-selective electrodes, HACH combination nitrate electrode, and the CARDY nitrate meter on pepper petioles over five sample dates (n = 160). The electrode values were compared to the Cd reduction method performed on a Lachat automated ion analyzer with flow injection analysis. Thirty petioles were collected from plots of each of several N rate studies and the sap expressed by a hand-held garlic press. Correlation among the techniques were similar (r > 0.9), but the CARDY meter constantly read 100 to 175 ppm higher than the HACH. Across all dates the standard deviation of the difference, compared with the Cd reduction, for the HACH = 16 ppm, while for the CARDY it was 50. While the CARDY meter is easier to use and has fewer steps, the HACH electrode values were closer to the true readings and less erratic. One must use care when interpreting nitrate sufficiency value ranges with different quick-test techniques.

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Perennial legumes ground covers were evaluated in pecan (Carya illinoinensis) orchards to supply nitrogen and increase beneficial arthropods. Ground covers were `Kenland' red clover (Trifolium pratense), `Louisiana S-1' white clover (Trifolium repens), a mixture of these two legumes, or bermuda grass (Cynodon dactylon), each in 5 ha plots. Nitrogen was applied at 0-200 kg·ha-1 N in 50 kg intervals to bermuda grass plots, and was omitted on the legumes. Aphids feeding on the legumes attracted lady beetles; however, lady beetle populations in the tree canopies were not affected by ground cover treatment. The most abundant lady beetle species in legumes were Coleomegilla maculata lengi (77%) and Coccinella septempunctata (13%); whereas, dominant species in tree canopies were Coleomegilla maculata lengi (33%). Olla v-nigrum (20%). Cycloneda munda (18%) and Coccinella septempunctata (15%). Several other beneficial arthropods were sampled in legumes and tree canopies. Aphid populations feeding on pecans were low (peak population ≈ 2 aphids/leaf), and not affected by ground cover treatment. Legumes supplied the equivalent of applying 68-156 kg·ha-1 N.

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Abstract

Vegetable garden planning software for personal computers is gaining in popularity (3). The program described herein (GARD-PLAN) provides a listing of vegetable crops from which the user makes selections. Cultural recommendations are made, and yields are projected based on the selections made in the program. A 3-year study to determine the dollar value of vegetable gardens in the 40 counties in North Dakota showed that the average value per garden was about $400, with the highest-valued garden at over $1200 (1). Therefore, vegetable gardening can result in significant savings relative to fresh produce purchased during the growing season.

Open Access