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Sunday, April 10, 2016

Spring Rain Can Bring Several Problems to Landscapes

The rain this past weekend may have brought some problems along with it, the same as it did last year after a rain like this. Problems might develop during the coming week or, with some plants, even extend into May or later.
Japanese euonymous with powdery mildew
Plants like roses may show signs of powdery mildew disease. This disease is aggravated by cool, wet weather, splashing rain, followed by warm weather. It appears as a white powdery dust on the leaves that can kill them. This disease is usually weak in our climate mostly because of our low humidity and cloudless days.
Rose with powdery mildew
Pull off a few leaves so air can circulate through the plants and allow them dry out naturally. Apply a preventive spray of a conventional fungicide for roses, sulfur dust or Neem oil. Lower humidity, air movement and sunlight in the coming days may clear up this problem without pesticides on some plants.
Fire blight in pear
            Another problem on European and Asian pear as well as some apples is fire blight. This disease is particularly virulent too many members of the Rose family such as many of our fruit trees.
If these trees were flowering during this rain it is possible this disease may show its ugly head toward the beginning of May. Look for jet black dieback on new growth, usually very close to the infected flowers.
Classic symptoms of fire blight in pear
Cut out these stems or branches 12 inches below the infection and sterilize pruning tools after each cut. Bag these infected plant parts and get them off of your property.
Pomegranate disease due to wet spring weather
            Pomegranates that are flowering may develop fruit with a black interior later in the season. This disease can be the result of wet weather when they are flowering. This disease may not appear on fruit until quite a bit later in the season. It does not spread beyond the fruit and the fruit is inedible.
Mushrooms popping up in wood mulch after rain

            Mushrooms frequently pop out of the ground after a rain like this. Nothing to worry about but knock them over with a rake and keep them away from your pets. They are feeding off of decaying wood or wood chips in the soil or on the soil surface. They are good guys.

1 comment:

  1. Comment from Tom Spellman at Dave Wilson Nursery to me in an email.... He is talking about the disinfectant needed on pruning shears and saws when removing infected limbs and shoots.
    Hey Bob, just a comment on the section where you mentioned Fire Blite. Studies have shown that the only reliable disinfectant for sterilization is a 50/50 mix of household bleach and water. Alcohol and other disinfectants have proven to be almost useless.