Search Results

You are looking at 1 - 10 of 12 items for

  • Author or Editor: Donn Johnson x
  • All content x
Clear All Modify Search
Free access

Donn T. Johnson

Thorny erect blackberries (Rubus spp.) were evaluated for yield and cane vigor as affected by galls produced by the rednecked cane borer Agrilus ruficollis (F.). Galling in `Cherokee' significantly (P < 0.001) decreased the count of berries and the weight of berries per centimeter of live cane. Winter injury, water stress, and nutritional stress induced by galls increased the amount of dead wood per cane. Galling did not affect the length of live laterals per `Cherokee' cane. For `Comanche' and `Cheyenne', the amount of dead wood per cane increased as gall counts increased. In contrast, the length of live laterals per cane increased for `Comanche' and decreased for `Cheyenne' as gall counts increased. The weight of berries and the count of berries per centimeter of live cane for `Comanche' and `Cheyenne' were not related to the count of galls. Of the four cultivars, `Shawnee' produced the most berries and greatest weight of berries per centimeter of live cane when canes were free of galls. Conversely, when galls exceeded two per cane, `Shawnee' yielded least, followed by `Comanche', `Cheyenne', and `Cherokee'.

Full access

Joe R. Williamson and Donn T. Johnson

Agricultural monocultures with intensive pest management practices reduce diversity and create instability in agricultural ecosystems, thereby increasing reliance upon pesticides. This study compares the influence of three insect pest management programs in vineyards on arthropod diversity as well as parasitism and control of grape berry moth (Endopiza viteana), the key pest of grapes (Vitis labrusca) in eastern North America. Vineyards in Bald Knob, Hindsville, Judsonia, Lowell, and Searcy, Ark., were managed with a range of intensity of insecticide use, a reduced insecticide program with Exosex-GBM dispensers for mating disruption, or no pesticide use in abandoned vineyards. Arthropod diversity and carabid (Carabidae) density in each vineyard was sampled with pitfall traps. Grape berry moth flight was monitored by pheromone traps. Grape berry moth–infested grapes were collected from the field and reared in the lab until parasites or moths emerged. There were significant differences in arthropod diversity between vineyard sites, with Shannon diversity index values generally higher in woods and managed vineyards with conventional sprays and/or mating disruption than in abandoned sites. Shannon index values for arthropod diversity were significantly lower at the vineyard edge in Searcy (recently abandoned), vineyard center and edge in Bald Knob (abandoned), and the vineyard edge in Hindsville (conventional sprays). In 2003, carabid density was significantly highest in the edge and center of the Hindsville vineyard (high insecticide usage) and the abandoned Bald Knob vineyard had significantly lowest carabid density. Apparently, insecticide sprays resulted in more food on the vineyard floor for carabids. The vineyard floor management was too variable among vineyards to deduce its effect on carabid density. With some exceptions, low-spray and no-spray vineyards generally showed greater diversity and parasitism of grape berry moth than high-spray vineyards. Parasitism was higher in some high-spray vineyards than in low-spray with mating disruption vineyards. Grape berry moth flight and berry damage were more dependent on spray timing than intensity. This study demonstrates that insect pest management programs impact arthropod diversity and parasitism. Further testing is needed to determine why parasitism of grape berry moth decreased in the vineyards using the mating disruption tactic.

Free access

Curt R. Rom, Jason McAfee, and Donn Johnson

Apple cultivar development is an important program necessary to sustain the existing fruit industry and stimulate new production systems for Arkansas and the region. The cultivar development program has two parts. First, currently available cultivars are tested with multiple trees for multiple years. Second, about 150 advanced selections from the Arkansas apple breeding program are evaluated in trials with multiple trees (2nd test) and in replicated trials (3rd test). The goal of both programs is to identify cultivars that have potential in the local production systems and for Arkansas' markets, and to identify those cultivars which are not adapted to the region. All cultivars and advanced selections are evaluated for ∂35 qualitative and quantitative characteristics, including time of bloom, time of harvest, length of harvest season, fruit aesthetic and internal quality, environmental adaptability especially to heat and high light, and insect and disease susceptibility. Primary diseases for which cultivars and selections are screened include fireblight, cedar apple rust, powdery mildew, black rot, white rot and bitter rot. Primary insect pests include mites, codling moth, plum curculio and Japanese beetle. Cultivars are evaluated in the field, under standard management conditions for five to seven years of production before summary evaluation. The program has identified cultivars including traditional cultivars, new cultivars, and heritage cultivars adaptable to the local and regional climates and suitable for those markets.

Free access

Krista L. Kugler-Quinn, Curt R. Rom, and Donn T. Johnson

Single leaf gas exchange measurements were taken at a range of light intensities from 20 to 1500 μmol·m-2·s-1 PAR under greenhouse conditions on `Washington Spur'/EMLA seven potted apple trees subjected to either 1500 cumulative mite days (CMD) European Red mite (ERM) damage or no mite damage. 1500 CMD ERM damage significantly reduced assimilation (A) over all light intensities for leaves present during mite damage at 6 days after the mite population had reached the 1500 CMD level and the mites were killed. Mite damage did not significantly affect A of either leaves present during mite damage or leaves produced after the mites were killed on any other sampling date. However, a trend of reduced A of leaves present during mite infestation on the mite-damaged trees was apparent on all sampling dates after the mites were killed. Evapotranspiration (E) was not affected by mite damage. The mite damage by light intensity interaction did not have a significant effect on A or E on any sampling date.

Free access

Curt R. Rom, Donn Johnson, Mark Den Herder, and Ron Talbert

Twelve apple orchards and an experimental orchard were evaluated in 2 years for weed population and diversity, primary pests (codling moth, oriental fruit moth, plum curculio and mites), primary diseases, soil water content, and 37 horticultural attributes describing tree growth, fruit growth, productivity, tree nutrition, and management intensity. Data were collected at 2 week intervals. The experimental orchard contained three apple cultivars grown in three orchard floor management systems.

Increased weed ground cover related to earlier and increased mite predator populations in trees, decreased pest mite-days, but reduced tree and fruit growth. Grass weed species appeared more detrimental to tree growth than broadleaf species. Tree training intensity was negatively related to canopy density, and incidence of pests and diseases. Reductions in fruit size and quality were more closely linked to weed competition, and earliness and degree of pest mite infestation than to crop load.

Free access

Heather Friedrich*, Curt R. Rom, Jennie Popp, Barbara Bellows, and Donn Johnson

Interest IN and conversion to sustainable agriculture practices, such as organic agriculture, integrated pest management or increasing biodiversity, has been increasing for a number of years among farmers and ranchers across the United States In order to meet the needs of producers, university researchers and educators must adapt their program areas to reflect this change toward sustainable agriculture practices. Although consumers, producers, and extension workers have been surveyed regarding their attitudes and interests in sustainable agricultural practices, few surveys have examined sustainable agriculture perceptions among university agriculture professionals. The object of this study was to survey 200 agriculture professionals, including research scientists, classroom educators of the Land-Grant agricultural college and the Cooperative Extension service of a southern state with a traditional agricultural economy in order to determine their perceptions and attitudes toward sustainable agriculture and to gather information on current research and education activities relevant to sustainable agriculture. Seventy-eight questions were asked concerning professional incentives, personal and professional importance of topics under the sustainable agriculture rubric, current research and educational activities, and demographics. By conducting this research we hope to identify factors that are an impedance or assistance to future research and education to support sustainable agriculture. The survey findings will provide a foundation for directing and developing agriculture research and education programs for row crops, fruit, vegetable and livestock production.

Free access

Curt R. Rom, R. Andy Allen, Donn T. Johnson, and Ronald McNew

The NE-183 project was established in 1993 and the first trial planted in 1995 with the objective of evaluating new apple cultivars for horticultural, pest and disease resistance, and qualitative characteristics. Arkansas (AR) is the southernmost location for the initial planting. The following cultivars are in AR trial: `Arlet', `Braeburn', `Cameo', `Creston', `Enterprise', `Fortune', `Fuji', `Gala Supreme', `Ginger Gold', `GoldCrisp', `Golden Delicious', `Golden Supreme', `Goldrush', `Honeycrisp', `NY75414-1', `Orin', `Pristine', `Sansa', `Shizuka', `Suncrisp', `Sunrise', and `Yataka'. Bloom of `Braeburn', `Yataka', `Orin', `Gold Supreme', `Fortune', and `Enterprise' were early and may be exposed to annual spring frosts. The following cultivars ripened in July or August and may be too early for southern markets: `Pristine', `Sunrise', `Sansa', `Ginger Gold', `Arlet', `Honeycrisp', `Golden Supreme', and `Orin'. The following cultivars were very precocious and had yields >7.5 kg/tree in the third growing season: `Fuji', `Enterprise', `Creston', `Golden Delicious', `Ginger Gold', `Suncrisp', and `Goldrush'.

Free access

Jayasree Ravi, Donn T. Johnson, Barbara A. Lewis, and Curt R. Rom

In 1995, greenhouse and orchard experiments of 11 apple cultivars were conducted in Fayetteville and Clarksville, Ark. Weekly cumulative mite days (CMD) were regressed against leaf bronzing (colorimeter value L) and compared among cultivars. European red mites, Panonychus ulmi and two-spotted spider mites, Tetranychus urticae, were found on leaves. `Liberty', `Royal Gala', and `Stark Spur Red Rome Beauty' had significantly more mites (>1940 CMD) than did `Arkansas Black' (1303), `Jonafree' (1150), and `Northern Spy' (973). A low CMD on `Northern Spy' caused leaves to bronze faster [y = 29.04 + 0.006(x); R 2 = 52, P = 0.0002] than did a high CMD on `Liberty' [y = 30.41 + 0.0027(x); R 2 = 70, P = 0.0001]. Field estimates were made of spider mites/leaf and bronzing from 20 June to 7 Aug. `Stark Spur Red Rome Beauty' and `Stark Spur Law Rome' had significantly more CMD than did `Northern Spy' and `Arkansas Black'. Apple cultivars differed in carrying capacity to mites (susceptibility) and how fast leaves bronze in response to mite feeding. Cultivar differences in hairiness of the lower leaf surface were not correlated to CMD.

Full access

Christopher I. Vincent, M. Elena García, Donn T. Johnson, and Curt R. Rom

The broad mite (Polyphagotarsonemus latus) was found in association with leaf-curling symptoms on primocane-fruiting blackberry (Rubus rubus) in Arkansas in 2007–2009. Broad mite had not been previously reported on blackberry. The plots sampled in this study were part of a study comparing harvesting in the fall versus harvest in spring and fall, high tunnels versus ambient conditions, and three genotypes, all under organic production. Leaves were sampled, broad mites per leaf counted, and leaf area and trichome density measured. Results indicated that broad mite is capable of overwintering in a moderate temperate climate and that it reduces leaf area of primocane-fruiting blackberry. The fall-only harvest system had fewer broad mites than fall and spring harvest. There were a range of genotype effects on broad mite populations, including one genotype, ‘Prime-Jan®’, on which broad mite populations remained low, and one genotype, APF-46, on which mite populations grew significantly. Observations indicate that the broad mite may be a pest of ‘Prime-Ark® 45’, another primocane-fruiting cultivar.

Full access

Tahir Rashid, Donn T. Johnson, Don C. Steinkraus, and Curt R. Rom

Insecticides were compared for control of codling moth (Cydia pomonella) and oriental fruit moth (Grapholita molesta), and effects on european red mites (Panonychus ulmi) and predatory mites (Neoseiulus fallacis) in `Red Delicious' apple trees (Malus ×domestica). Ten days after treatment with azinphosmethyl, celerylooper (Anagrapha falcifera) nuclear polyhedrosis virus, rotenone-pyrethrin, or codling moth granulosis virus, fruit damage by larval codling moth and oriental fruit moth was significantly less than trees treated with Bacillus thuringiensis var. kurstaki or water (control). Trees treated with azinphosmethyl or celery looper nuclear polyhedrosis virus had fewer damaged fruit where larvae exited than did other treatments. By 21 days after the last treatment, all treatments had significantly more wormy or damaged fruit than did azinphosmethyl. At 10 days after treatment, the two viruses were more deleterious to codling moth than to oriental fruit moth causing a <1:3 ratio of these larvae compared to >3:1 ratio for the other treatments. On 16 June, 100 predatory mites were released onto the trunk of each tree. The minimum ratio of predatory mites to european red mites (>1:10) that favors biological control of european red mites occurred in all treatments by 14 July, except those treated with azinphosmethyl or rotenone-pyrethrin that had significantly more cumulative mite days of european red mites than the other treatments. The use of azinphosmethyl delayed biological control of the european red mites until 27 July whereas rotenone-pyrethrin treatment never attained biological control of the mites.