Disease-Resistant Fruits

Sunday, February 19th, 2017 by Jenny Watts
    • Potatoes are available now for spring planting. Choose from red, white, yellow and blue varieties as well as the popular fingerlings.
    • Spray for peach leaf curl with copper spray. Peach and nectarine trees may suffer from this fungus disease without a protective spray.
    • Roses should be pruned now. After pruning, remove all old leaves on and around the bushes and spray plants with Neem oil to prevent early pest and disease problems.
    • Asparagus will provide you with delicious, low-priced spears for years to come if you plant them now from dormant crowns.
    •  Give someone you love a pretty red Cyclamen today.

Disease-Resistant Fruits

Wet spring weather is prime time for diseases of all kinds, which can make leaves unsightly and even damage flowers. But it is especially hard on fruit trees causing diseases that last into the summer and damage the fruit as well as the foliage.

Spraying is typically done through the springtime to inhibit disease spores, but an even more successful way is to plant disease-resistant varieties. This is particularly beneficial for apples, which are prone to scab and cedar-apple rust; pears, which are prone to fireblight; peaches, which are prone to peach leaf curl; and apricots, which are prone to brown rot.

One of the best apple varieties for disease resistance is ‘Liberty’. This dark red apple has yellowish flesh that is crisp, juicy and fine flavored. It is primarily a dessert apple and it makes a fine pinkish applesauce. It is not susceptible to scab and very resistant to other apple diseases.

Other apples that are resistant to scab are ‘Golden Russet’, with crisp, aromatic, creamy yellow flesh and excellent sweet flavor; and ‘York Imperial’, a crisp, juicy apple with semi-sweet flavor that is a good keeper. ‘Empire’, a sweet and juicy red apple, and ‘Spartan’, with pure white, crisp, juicy flesh, are resistant to both fireblight and scab. ‘Stayman Winesap’, a late red apple with a lively flavor, is resistant to fireblight. ‘Honeycrisp’, a sweet, crisp apple, has some resistance to scab.

Some years, when the weather is just right, we can have a bad problem with fireblight on pears. It is a good idea to plant at least one resistant variety. Look for ‘Harrow Delight‘, with fruit similar to ‘Bartlett’, and ‘Warren’, whose smooth flesh is juicy and buttery with superb flavor. ‘Magness’, with soft, juicy, sweet flesh, and ‘Moonglow’, a large fruit for fresh use or canning, are also fireblight resistant.

Asian pears, which have round, juicy, crisp-like-an-apple fruit, can also be attacked by fireblight. ‘20th Century’, with sweet, mild-flavored fruit, and ‘Shinko’, with sweet, flavorful fruit, are both resistant to fireblight.

Peach trees can be severely damaged by peach leaf curl. ‘Frost’ peach is a delicious, medium-sized yellow freestone that is very resistant. So is ‘Q-1-8’, a semi-freestone white peach that is sweet and juicy with a sprightly flavor, and ‘Indian Free’, a white peach with red streaks through the fruit. It is tart until fully ripe when it develops a rich, distinctive flavor.

Apricots can have trouble with brown rot, which causes fruit to rot on the tree forming mummies. It is a problem when we have moderate temperatures and moist weather during bloom. ‘Harcot’, which has medium to large fruit with a sweet, rich flavor, is resistant to this disease.

Your orchard will be easier to maintain if you choose disease-resistant varieties whenever you can.

Watch Out for Plant Diseases

Wednesday, May 26th, 2010 by Jenny Watts
    • Tomatoes are the most popular summer vegetable. Choose from the many varieties available now so you can enjoy delicious home-grown flavor.
    • Petunias can be planted now. Their bright flowers will bloom all summer in hot, sunny locations and they will take a light frost.
    • Plant an herb garden in a container near the kitchen door for convenient fresh spices like basil, oregano, parsley and thyme.
    • When you plant your vegetable garden, why not grow a little extra to donate to the food bank this summer.

A Year for Plant Diseases

Any plant can be attacked by disease organisms. During wet spring weather, plant diseases are very common. Bacterial infections, fungi and viruses may be attacking some of your plants, so keep a sharp eye out for problems.

If soil is waterlogged, plant roots may deteriorate rapidly, largely due to the lack of oxygen in the soil. Waterlogged soil also favors the development of diseases such as damping-off and root rot fungi. Stems of annual and perennial flowers and vegetables, may darken and get soft, causing the plants to die. There is no cure for this problem.

Leaf diseases can be due to either fungi or bacteria. Powdery mildew, fungal leaf spots, and rusts are fungi which are spread by rain. You can’t remove the problem from the leaves it is on, but you can protect new growth and uninfected leaves by spraying with a preventative spray. Neem oil is a non-toxic spray that has proven to be quite effective.

Peach leaf curl is a fungus that infects the leaves before they open in the spring. The puckered and blistered leaves turn bright red with a white powdery layer over the leaf surface. Affected leaves will drop prematurely and a second set of leaves will come out that are usually not affected. Preventative spraying must be done during the dormant season and in severely wet springs, such as this, it may not be very effective. Remove the curled leaves, preferably before the white powdery spore layer develops, and dispose of them.

Bacterial leaf spots are very common in wet weather. These black or dead patches may be surrounded by a yellow margin. Usually when the weather dries out, the new growth will be unaffected, but it is a good idea to remove infected leaves and clean up dead leaves under the plant.

Bacterial canker often affects plum and cherry trees. Typically, a tree will push out new growth in a normal manner, then suddenly the leaves wither and die. The plants cannot pull up moisture into the leaves because the canker has girdled the trunk or branch of the tree. There is not much you can do about this condition, except prune out affected branches in the summer.

Viruses can also affect plants. Many viruses do not harm plants, such as those that cause variegation on leaves or flowers. But some can distort leaves or fruits, and the only control for these is to destroy infected plants and wash hands and tools so that you do not spread the problem to other plants.

If you see a disease problem that you need help with, pick several leaves in different stages of development, seal them in a plastic bag, and take them to your local nursery for identification and help. You may find some unusual plant problems in the garden this year.