Resistant Apple Cultivars Research Articles

FIELD PERFORMANCE AND FRUIT QUALITY OF SCAB RESISTANT APPLE CULTIVARS IN THE LOMBARDIA (ITALY) REGION

Two experimental fields have been planted in Lombardia with scab resistant apple cultivars, one in the plane, in the Po valley (Lodi province) at 85 m above sea level, the other in Valtellina at 400 m above sea level. Eleven cultivars (Brina, Baujade, Enterprise, Golden Lasa, Golden Mira, Golden Orange, Gold Rush, Nova, Primiera, Sir Prize and Topaz) are present in both localities, five more (Criterion, Harmony Delorina, Red Early, Summerfree and Sansa) are present only at Arcagna, while seven more are present only in Valtellina (Florina, Freedom, Prima, Rajka, Rubinola, Rosana, Otava). In the Valtellina orchard there are also thirteen new cultivars not yet commercially available (CLR13T40, CLR13T45, CLR20T14, CLR20T22, CQR10T17, HER4T175, Pri Coop 11, Pri Coop 17, Pri Coop 25, Pri Coop 34, Pri 2463/101, Pri 75 441/67, PSER11T27). In both localities observations were made on the agronomic behaviour of trees (vigour and branching of shoots, susceptibility to scab or to other pathologies of leaves or fruits, fruit set, fruit bearing, etc.); phenological phases (time of budding, flowering, ripening of fruits) were recorded; fruit morphological characteristics (weight, shape, colour, skin russeting etc.) were observed at harvest. Fruits were moreover analyzed at harvest and after storage for chemical and physical characteristics. Observations on performance of cultivars and fruit quality are shown and discussed. The eleven cultivars common to both localities are compared as regards the quality of fruits grown in different environments.

Evaluation of Malus species and cultivars at the Fruit Genebank Dresden-Pillnitz and its use for apple resistance breeding

Using the results of evaluation of Malus accessions during the last 20 years more than 15 new resistant apple cultivars were selected. The breeding aim was the combination of different kinds of resistance with good fruit quality. The best of these cultivars enclose resistance against Venturia inaequalis, Podosphaera leucotricha, Erwinia amylovora, Pseudomonas syringae, Panonychus ulmi and winterfrost. Different scab resistance sources (Vf, Vr, VA) found among the Malus species are combined in the most recent breeding lines.

Elicited cell suspension cultures of apple (Malus×domestica) cv. Liberty produce biphenyl phytoalexins

Yeast extract treated cell suspension cultures from a scab (Venturia inaequalis) resistant apple cultivar, Malus×domestica cv. Liberty produce dibenzofuran and biphenyl compounds as part of their defense system against fungal invasion. We have isolated and identified three biphenyl derivatives, 4-hydroxy-3,5-dimethoxybiphenyl (aucuparin), 2′,4,-dihydroxy-3,5-dimethoxybiphenyl (2′-hydroxy-aucuparin) and 2′-O-β-d-glucopyranosyl-4-hydroxy-3,5-methoxybiphenyl (2′-o-β-d-glucopyranosylaucuparin) from the cells and the medium and show here their chemical properties. Although this is the first identification of 2′-glucopyranosyl-aucuparin, its aglycone, 2′-hydroxyaucuparin, and aucuparin have been reported previously [Kokubun, T., Harborne, J.B., Phytochemistry, 1995, 40, 1649–1654.] from fungus infected wood of Malus species. Production of an array of dibenzofuran and biphenyl derivatives in response to fungal attack may be an important part of the disease resistance mechanism of scab resistant apple cultivars.

THE NORTHEAST SARE (LISA) APPLE PRODUCTION PROJECT

Developing sustainable production systems based on the disease resistant apple cultivars (DRACs) and IPM techniques is a key objective of this multidisciplinary project involving 19 principle investigators across 5 cooperating institutions. Cultivar selection is a crucial decision for an apple grower which will impact the farm's competitiveness and profitability for many years. Factors that growers consider when deciding what cultivars to plant include consumer acceptance and marketability; winter hardiness; yield potential; fruit storage qualities, color, taste, and size; and potential pest management problems. These factors are being researched in this project. Disease resistant orchards will undoubtedly present new economic considerations to growers, wholesalers, and processors. A further objective is to provide economic analyses of alternative techniques and to forecast the impact of changes in production systems on the Northeast apple industry. Apple growers must have access to research-generated information that addresses the critical issues facing them Rapid information dissemination is a high priority of this project. The Northeast Sustainable Apple Production Newsletter has over 1200 active subscribers across the United States and in 7 foreign countries. The Management Guide for Low-Input Sustainable Apple production has been well received and continues to be requested world-wide.