Rain is a Good Thing in the Desert. Right?

            It rained this past week. That’s good news, right? Maybe. If you are growing Asian pears, European pears like Bartlett or apples you might see a disease pop up beginning around May. Infection starts as black dieback of new growth like it was burned by fire.

Fire Blight

This is an extreme case of fireblight on one of the pome fruits such as apple, pear, quince or Asian pear. It usually is seen in mid to late spring when all the growth is going gung-ho. 

Its normally not as obvious as the first picture. That was unusual. This is more common. Dieback of new growth and oftentimes its black just like fire hit it.

This disease is called Fire Blight and can lead to tree death if not controlled when it’s first seen in May or June. It can be common several weeks after spring rains particularly if trees were flowering during spring rainy weather.

            Fire Blight is a bacterial disease, so fungicide sprays won’t work. The best thing is to  remove the infected limb by pruning generously. Sanitize the blades of any pruning tools with 70% alcohol after each cut. Then bag this diseased black growth and get it off the property ASAP.

Bunch Rot

      

This was one of the bunch rot diseases a local pathologist identified as Apergillus. It comes in many forms but oftentimes for homeowners they will control it with sprays or dusts of a copper fungicide such as Bordeaux.

      Another disease I saw pop up last year in grapes was a Bunch Rot disease but not really seen until the bunches got big. However, the disease started during spring, rainy weather like we just had. For homeowners, copper containing fungicide sprays work best to contain this disease with the first of three sprays starting now as the grape bunches first start to form.