Search Results

You are looking at 1 - 10 of 208 items for :

  • fire blight x
Clear All

characteristics. Although Cotoneaster generally is robust and easy to cultivate, many taxa are susceptible to the bacterial disease fire blight caused by Erwinia amylovora . Disease susceptibility limits the potential of the genus in landscape applications. For

Free access

adaptation studies ( Barut, 2000 ). Fire blight, caused by the bacterium Erwinia amylovora (Burr.) Winslow et al., is a disease that affects many Rosaceous species with apple ( Malus sp.) and pear ( Pyrus sp.) being of the greatest economic significance

Free access

is their susceptibility to rootstock blight, a discrete fire blight infection of the rootstock. Fire blight, incited by the bacterium Erwinia amylovora [(Burr.) Winslow et al.], is a common bacterial disease of rosaceous plants ( Vanneste and Eden

Free access

for blossom thinning of fruit trees ( Schupp et al., 2008 ). Several extensive trials were conducted in commercial peach orchards, but as a result of concerns about fire blight, only one preliminary trial was conducted on apple at the Penn State Fruit

Free access

foundation plants, as hedges, in parking lots, or in a mass planting along roadsides. Although cotoneasters often are attractive and utilitarian for landscaping, most available cultivars are susceptible to the bacterial plant disease fire blight caused by

Open Access

Abstract

Of 20 cultivars of pear (Pyrus spp.) evaluated for their degree of resistance to fire blight, caused by Erwinia amylovora (Burr.) Windslow et al., following 6 years of epiphytotic conditions, 9 were rated as resistant: (in descending order) ‘Magness’, ‘Moonglow’, ‘El Dorado’, ‘Cornice’, ‘Maxine’, ‘Mac’, ‘Dawn’, ‘Duchess d’Angouleme’, and ‘Kieffer’. Small plots of trees, sufficient to determine very susceptible cultivars, are not adequate to evaluate resistant cultivars.

Open Access

Twenty-five cultivars of red raspberry (Rubus idaeus L.) and one purple raspberry (R. occidentalis L. × R. idaeus L.) were evaluated for their resistance to fire blight caused by Erwinia amylovora (Burr.) Winslow et al. Actively growing raspberry cane tips were wound inoculated with three isolates of the pathogen and disease development was assessed over 17 days. Three methods of evaluating resistance were used: area under the disease progress curve (AUDPC), a weighted AUDPC called the area under the disease severity curve (AUDSC), and lesion length. A wide range of resistance levels was observed, but no cultivars were symptomless. Primocane-fruiting cultivars tended to be more resistant than floricane-fruiting ones. Of the three E. amylovora isolates used in this study, one was significantly more virulent than the other two, but no cultivar × isolate interaction was detected.

Free access

Abstract

The first occurrence of fire blight on thornless blackberries (Rubus spp.) was reported in Illinois in 1976 (7, 8). Infections appeared either at the cane tip and proceeded basipetally, at axillary buds, causing cane girdling, or on flower/fruit clusters. Diseased portions of the canes were necrotic, purplish-black, and the tips were curved. Lesions were characteristically water-soaked and produced abundant bacterial ooze. Infected fruits did not develop to maturity, became brown, dried, very hard, and remained attached to the fruit pedicel. Frequently entire fruit clusters were infected but generally 1 or 2 fruits in each cluster escaped (Fig. 1). Mummified berries were commonly present on the 4 commercial cultivars (‘Thornfree’, ‘Dirksen Thornless’, ‘Black Satin’, and ‘Smooth-stem’) as well as several unnamed selections of similar genetic background to these cultivars. One seedling selection (SIUS 68-6-15) exhibited about 65% fruit infection. A bacterium was isolated from these fruits and from infected stems. The organism was morphologically and physiologically identical to, but pathogenically different from Erwinia amylovora (Burr.) Winslow et al. isolates from apple and pear.

Open Access

Abstract

Natural infections of fire blight following 2 years of epiphytotic conditions caused severe blight damage in the pear cultivar collection at Beltsville, Maryland. Of 522 cultivars rated with the USDA fire blight scoring system, 88% were highly susceptible, 2% were moderately susceptible, 4% were moderately resistant, 5% were highly resistant, and 2% had no blight symptoms. Names of pear cultivars in each resistance class are listed.

Open Access
Authors: , , , and

Kentucky is one of seven states in the southeast evaluating 13 Asian pear cultivars for suitability to the region. The cultivars were planted on a (20′ × 10′) spacing in 1989 at three separate locations. Data on time of bloom, tree growth, fire blight susceptibility and fruit quality and yield were collected. This study demonstrates the variability seen in Asian pear cultivars in response to site. There was a significant site by cultivar interaction for fire blight. The Princeton site had significantly more fire blight than either Lexington or Quicksand. Four cultivars, Niitaka, Shin Li, Shinko and Shinseiki had low fire blight ratings which were not significantly different between the three sites. Asian pear growth rates were significantly different between the three sites, but cultivar growth rates were not. Tree growth rate showed a significant negative correlation to fire blight rating. That is infected trees did not grow much. Initial findings show Shinko, Shinseiki and Niitaka to have some tolerance to fire blight spread and to produce good yields of attractive fruit. However, Niitaka had a very tough skin with a tendency towards fruit cracking. The cultivar Shin Li which also had fire blight tolerance did not produce fruit or flowers.

Free access