Prevalence of Myclobutanil Resistance and Difenoconazole Insensitivity in Populations of Venturia inaequalis.

Demethylation inhibitors (DMIs) are a class of single-site fungicides with high levels of protective and curative efficacy against Venturia inaequalis, the causal agent of apple scab. To determine the prevalence of resistance to the DMI fungicide myclobutanil, 3,987 single-lesion conidial V. inaequalis isolates from 141 commercial, research, and baseline orchard populations were examined throughout New England, the mid-Atlantic, and the Midwest from 2004 to 2013.

Prevalence and Stability of Qualitative QoI Resistance in Populations of Venturia inaequalis in the Northeastern United States.

Quinone-outside-inhibitor (QoI) fungicides are a safe and effective means of managing apple scab caused by Venturia inaequalis. To determine the prevalence of both quantitative (partial) and qualitative (complete) QoI resistance in V. inaequalis in the northeastern United States, we sampled single-lesion conidial isolates (n = 4,481) from 120 commercial and research orchards from 2004 to 2011 with a range of exposure to QoI fungicides from none to several applications a year.

Etiology of Moldy Core, Core Browning, and Core Rot of Fuji Apple in China.

'Fuji' apple fruit were collected in Shaanxi Province, China, and 186 fungal isolates were obtained from the fruit core region. Fungi were isolated from fruit with symptomless core regions, as well as from the core regions of fruit showing browning, typical moldy core, or core rot. Based on phylogenetic and morphological analysis, all fungi were identified to species.

Pathogenic diversity of Phytophthora sojae and breeding strategies to develop Phytophthora-resistant soybeans.

Phytophthora stem and root rot, caused by Phytophthora sojae, is one of the most destructive diseases of soybean [Glycine max (L.) Merr.], and the incidence of this disease has been increasing in several soybean-producing areas around the world.

A New View of Sooty Blotch and Flyspeck.

Sooty blotch and flyspeck (SBFS) fungi colonize the surface wax layer of the fruit of apple, pear, persimmon, banana, orange, papaya, and several other cultivated tree and vine crops. In addition to colonizing cultivated fruit crops, SBFS fungi also grow on the surfaces of stems, twigs, leaves, and fruit of a wide range of wild plants. The disease occurs worldwide in regions with moist growing seasons.

Analysis of Fire Blight Shoot Infection Epidemics on Apple.

Fire blight incidence and spread of the shoot blight phase of the disease was studied in four apple cultivars in replicated blocks over 4 years (1994 to 1997). Cv. York was highly susceptible, followed by 'Fuji' and 'Golden Delicious,' which were moderately susceptible, and 'Liberty,' which was least susceptible.

Production and Dispersal of Conidia of Leucostoma cinctum in Peach and Cherry Orchards Under Irrigation in Eastern Washington.

The objectives of this study were to determine the seasonal production patterns of Leucostoma cinctum conidia in peach and cherry orchards and the effects of irrigation on dispersal of conidia. Conidia were trapped throughout the year and were present in highest numbers during spring and summer on both cherry and peach. The pathogen was dispersed 1.

Effect of Inoculum Concentration and Calcium Salts on Infection of Apple Fruit by Botryosphaeria dothidea.

The objective of this study was to determine the effects of calcium salts on growth of Botryosphaeria dothidea and incidence of white rot. The relative virulence of five B. dothidea isolates was determined using the apple cultivars Fuji, Gala, Golden Delicious, Liberty, and York.

Assessment of an Alternative IPM Program for the Production of Apples for Processing.

Conventional and alternative integrated pest management (IPM) programs for managing arthropods and diseases affecting processing apple production were compared over 4 years. The effects of the two programs on populations of pest and beneficial insects, and on disease incidence and severity, were evaluated in the field and laboratory and at a commercial fruit processing plant by federal inspectors. The economic implications of the alternative management program were assessed by examining its relative costs and benefits compared with conventional management.

Effects of Calcium Salts on Apple Bitter Rot Caused by Two Colletotrichum spp.

The effects of three calcium salts on conidial germination, germ tube elongation, growth in vitro, and infectivity in the laboratory and field were studied for the apple bitter rot pathogens, Colletotrichum gloeosporioides and C. acutatum. Calcium chloride, calcium propionate, and calcium silicate at 1,000 μg of calcium per ml had no effect on conidial germination; however, calcium chloride and calcium propionate inhibited germ tube growth by 41 and 50% relative to the control, respectively.