A disease called fire blight, caused by a bacterium (Erwinia amylovora), has these symptoms. The causal bacteria are spread by wind-blown rain and insects. Fire blight is difficult to control in highly susceptible varieties. Avoid excessive nitrogen fertilizer. The blighted shoots and blossoms can be pruned out as they appear if you sanitize the pruning shears by dipping them in a 10 percent bleach solution or 70% isopropyl alcohol (rubbing alcohol) between cuts. Otherwise, prune the blighted shoots …
I missed pruning a few dead branches in an apple tree. Can I remove them in the summer?
The best time to prune is early in the Spring before bud break. Dead or broken branches can be removed anytime, but keep other pruning to a minimum.…
Should I wait until after a frost to harvest my apples?
No, harvest apples before the temperature drops below about 28°F. That is canopy temperature and will not necessarily be reflected by the thermometer on your porch.…
I have a 'Gala' apple tree. Would planting a 'Granny Smith' tree in my yard serve as a pollinator for the other?
Yes, ‘Granny Smith” would be a good choice. If you can’t find a ‘Granny Smith’ tree, then a ‘Mollies Delicious’ would work well. To see a pollination chart for apple varieties, refer to this article on Pollination of Fruit Trees.…
What are the disease-resistant apple cultivars recommended for Wisconsin?
The following are some of the cultivars that will grow well in Wisconsin:
• Redfree: This is an early season, medium-sized, attractive red apple. You can store these apples up to 30 days.
• Prima: Prima produces medium to large fruit, red blushed on yellow skin. Mild, juicy, white flesh matures a week before McIntosh. You can store this apple for one to two months.
• Priscilla: This is a medium to large apple if you thin trees adequately after …
What causes the yellow leaf spots that later develop a brown center on my apple leaves?
This a fungal disease called cedar-apple rust. Cedar-apple rust is a common disease of apple and crabapple. The fungus that causes the disease, Gymnosporangium juniperi-virginianae, is unusual because it must spend a phase of its life cycle as a parasite on Juniperus species, such as red cedar or ornamental junipers. Control: Grow resistant apple or crabapple varieties. Apple varieties that normally show good to excellent resistance to cedar-apple rust include ‘Red Delicious’, ‘McIntosh’, ‘Arkansas Black’, ‘Winesap’, ‘Mollies Delicious’, ‘Spartan’, …
How do I find out what variety my apple tree it is? Can my local Extension office tell me ?
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.…
When is the proper time to thin fruit on apple, pear, and peach trees?
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 …
How long can I store fresh apples?
Late-maturing varieties of apples will store for use throughout the winter if the fruit is hard, mature, and in perfect condition. Apples picked too green (unripe) are subject to a number of storage disorders, such as scald and bitter pit; if picked beyond maturity, they quickly become overripe in storage. Cool fruit as quickly as possible after harvest for best results. For most varieties of apples, the optimal storage temperature is 30° to 32°F with a 90% relative humidity. Higher …
How can I control insects and diseases on my apple tree?
Homeowners are often surprised at the damage pests can do to apples. It is not easy to grow apples as pretty as those seen in the grocery store. Several diseases and insects can damage apple trees. Besides spraying pesticides, other things can be done to reduce pest damage, but it is very difficult to grow quality apples without some kind of pesticide application schedule. Rake and destroy leaves in the fall to reduce damage from diseases that overwinter in infected …