Southern blight is caused by the fungus Sclerotium rolfsii. The disease is a problem primarily in the Piedmont apple-growing region in the southeastern United States. S. rolfsii is a widespread pathogen that affects several hundred plant species. For more information, read this article on Southern Blight in Apple Trees.
Answer provided by Alan R. Biggs, West Virginia University.…
Figure 1. Quince rust often forms orange tubes for spore dissemination. Photo: Alan R. Biggs, West Virginia University.Quince rust is a fungus disease caused by Gymnosporangium clavipes. The fungus infects fruit, but not leaves, of most apple cultivars. It infects both leaves and fruit of hawthorn.
Typically, an infection on apple fruit shows up first as a slightly raised purplish area on the calyx end of the fruit. On mature fruit, the lesion is sunken and dark green or purple …
Cedar-apple rust is a fungus disease of apple and cedar and spends parts of its life cycle on each host. It is caused by Gymnosporangium juniperi-virginianae. The fungus can infect leaves and fruit of most cultivars in the eastern region. A notable exception is ‘Delicious’, which is nearly immune. For more information, see this article on Cedar-Apple Rust.
Answer provided by Alan R. Biggs, West Virginia University.…
White root rot, caused by the fungus Scytinostroma galactinum (formerly Corticium galactinum), has been known as a parasite of apple trees for many years and is widely distributed (Canada to Texas and westward to the Pacific Coast, Europe, West Indies, and Japan). It is found in both bearing and non-bearing apple orchards. Other hosts include a wide variety of woody plants, ornamental shrubs, and herbaceous perennials, including white pine, ash, peach, blackberry, dewberry, Japanese wineberry, dogwood, sumac, white campion, …
Apple mosaic virus is one of the oldest known and most widespread apple viruses. The same virus can cause line pattern symptoms in plum and rose mosaic disease. Apple mosaic virus is related to Prunus necrotic ringspot virus. Apple trees infected with apple mosaic virus develop pale to bright cream spots on spring leaves as they expand. These spots may become necrotic after exposure to summer sun and heat. Most commercial cultivars are affected but vary in severity of symptoms. …
Many apple rootstocks are being evaluated for potential use in the United States by the NC-140 Multi-State Research Committee. These rootstocks have come from breeding programs in the United States (CG, G), Great Britain (M), Germany (PiAu and Supporter), Poland (P), Czech Republic (J-TE), Japan (JM), and Russia (B). Specific rootstocks that are currently under evaluation in NC-140 plantings include the following: B.9, B.10, B.7-3-150, B.7-20-21, B.67-5-32, B.64-194, B.70-6-8, B.70-20-20, B.71-7-22, G.11, G.16, G.41, G.202, G.935, CG.2034, CG.3001, CG.4003, …
Rootstocks are commonly propagated by layering to form large stool beds. The “mother plant” is set out in the field. The plant may either be mounded, or it may be trench layered. In mounding, the plant is cut off close to the ground. As the new shoots emerge from the mother plant, they are partially covered with soil or well-decomposed sawdust. The sawdust is renewed periodically during the growing season to prevent the base of the shoot from exposure to …
It is difficult to identify apple varieties unless your variety is a very common one. There are more than 10,000 named apple varieties in the world today. Sometimes we may be able to tell what “type” of apple it is (e.g., Jonathan type, Delicious type). When planting fruit in the landscape, it is important to create a plan showing where different varieties are planted. Put the plan in a notebook and a copy in the garage or planting shed.…
Apples and pears have three periods when some immature fruit drops naturally from the tree. The June drop (Zones 6 and 7) is the last one, and many growers feel that thinning should follow this drop. However, if a heavy bloom has coincided with good weather so that bees worked the blooms, the chances are that relatively few fruit will drop from the tree. In this instance, heavy thinning is required. The earlier the fruit are thinned, the greater the …