Question
About 2 yrs ago, we planted 2 Cleveland pear trees in our back yard, both with same growing conditions. We have been vigilant with water and feed, they have grown beautifully, but all of a sudden, abour 3 weeks ago, one of them had a few leaves start turning brown, on the whole stem.  Today we pruned them off, and found that the limbs are black,right in the middle, look burned, almost as if hit by lightening, but they were lower limbs. Hard to think it is tall enough to be hit by lightening.  What could be wrong with this one tree? Still has a few brown leaves scattered around, but no more damaged limbs.

Answer
Sounds like fire blight. Fire blight is one of the most devastating and difficult-to-control diseases of many fruit trees including apple and pear, and other rosaceous ornamental plants. Caused by a bacterium (Erwinia amylovora), it can spread rapidly, killing individual apple and pear trees when conditions are right for disease development and susceptible root stocks are used.

The first symptoms of fire blight occur in early spring, when temperatures are above 60 癋 and the weather is rainy or humid. Infected flowers turn black and die. The disease moves down the branch, resulting in death of young twigs, which blacken and curl over, giving the appearance of a "shepherd抯 crook." Leaves on affected branches wilt, blacken and remain attached to the plant, giving it a fire-scorched appearance. Slightly sunken areas, called cankers, appear on branches and the main stem. Many parts of the plant can be affected including blossoms, stems, leaves and fruit. During wet weather you may notice a milky-like, sticky liquid oozing from infected plant parts. Insects and rain can spread the disease.

There is no cure for fire blight, making disease prevention extremely important. Controls for fire blight include selecting tolerant varieties; using recommended cultural practices and sanitation measures; and applying insecticides and bactericides. Although these methods are not 100 percent effective, they help reduce disease severity.

Cultural Practices & Sanitation Measures: Reduce the spread of fire blight by removing and destroying all infected plant parts. Pruning cuts should be made 12 to18 inches below any sign of infected tissue. Disinfect all pruning tools between cuts using a solution of 1 part household bleach to 9 parts water. Succulent new growth is easily infected, if injured. Avoid excess nitrogen fertilization which results in excess succulent growth.

Pear trees can also be treated with streptomycin. Apply the first spray as soon as the blossoms open. Repeat at four- to seven- day intervals as long as blossoms are present.  Apply all chemicals according to directions on the label. Check with your local garden type store for this product.