What to do about fireblight and its affect on quince, pear and apple trees
Q I generally leave a lot of the garden/ yard work to my hubby; however, I’ve become concerned – as is he – about the health of our Asian Pear tree. The branches have become all black as have most all the leaves. The fruit is small and burnt-looking, and sucker plants are growing from the bottom/roots. My husband felt he might have overwatered it. I read what you wrote about the loss of black-looking branches just falling off trees and keeping suckers trimmed to ground level (too late). Is there anything we can do to save this tree, or should we cut it down and replace it, or let the suckers take over? Thank you for any advice you can give us.
It sounds like there are at least two issues here. The blackened branches, leaves, and fruit indicate that your Asian pear has been hit by fireblight. This is a bacterial disease that affects quince, Asian and European pears, and apples.
The first sign of fireblight appears in branch tips, which dry out and turn black as if they had been burned (that’s why it’s called fireblight). If caught early, the affected branches can be removed to prevent or slow spread to the main trunk. When pruning away fireblight, sanitize your pruners or saw with isopropyl alcohol or Lysol so you don’t spread the infection. Sometimes bleach is recommended because it is a very effective disinfectant, but it can be corrosive. If you do use bleach, remember to clean and oil your tools afterwards. Do not compost the infected branches – they should be burned or go directly into the trash.
Fireblight is spread to susceptible trees by bees (disappointing, I know). During flowering, honeybees carry infectious pollen from one tree to another. Ornamental flowering pears are a major source of fireblight. They can be infected, but unfortunately not killed by the disease. If you look at an ornamental pear, you’ll often see blackened branch tips similar to what you’re seeing on your Asian pear. Because life is not fair, these worthless trees can live years with fireblight, but useful fruit-bearing trees can succumb in a year or two.
If your tree has extensive damage, or if the damage has spread to the main trunk, I recommend removing it and replacing it with a fireblight-resistant variety such as Shinko or Kikusui.
Regarding the suckers growing below the graft — they should always be removed. They are from the rootstock and will not produce quality fruit. They also take energy from the fruit-producing part of the tree. Of course, since you’re probably going to remove this tree, this is kind of a moot point. Just something to remember when you plant your next tree.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; 949-809-9760; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; 951-683-6491 ext. 231; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu