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1-03-02
Question and Answer
Q. Each year, including this past one, some of
the new growth on my pear trees turns black and wilts. This year is the
worst ever. What causes this and what can I do about it? -- Ann Hunt,
West Lafayette, Ind.
A. Fireblight causes young twigs and flower blossoms
to wilt, blacken and die. Often the tips of blighted twigs become crooked,
resembling a shepherd's staff. Fireblight affects apples, pears and certain
ornamentals, including crab apples, hawthorns and firethorns.
This disease is caused by a bacterium that overwinters
in cankers on the branches, and, in the spring, droplets of amber-colored
ooze form from the cankers. Insects and splattering rain carry the bacterium
from the droplets to blossoms and twigs. Fireblight is most damaging in
years when spring temperatures are above normal with frequent rain.
Reduce the impact of the disease by pruning out
the infected twigs. Cut 8-12 inches below the diseased tissue, and sterilize
the cutting tools between each cut. A 70 percent denatured alcohol solution
or a 10 percent bleach solution will remove the bacterium from the pruners.
The most effective chemical control of fireblight
is an antibacterial spray labeled for fireblight. The spray will not kill
bacteria already present; it can only prevent new infection. Carefully
timed, repeated applications are necessary.
New growth is most susceptible to fireblight, so
avoid overfertilizing or excessive pruning, and remove any suckers that
develop on the trunk or main limbs. In the future, choose apple and pear
cultivars resistant to fireblight.
Q. My grandmother always fertilized my spring bulbs
with bonemeal. An employee at a garden center tried to sell me a bulb
fertilizer that cost more and said bonemeal wouldn't do the trick. Since
I just planted dozens of bulbs, I want to know how to take care of them.
What's the truth? -- Greg Anderson, Mishawaka, Ind.
A. Bonemeal isn't all it's cracked up to be. It
is falsely rumored to be the ideal fertilizer for spring bulbs, but it
is an incomplete fertilizer. Bonemeal supplies phosphorus to the plant
but no nitrogen or potassium. You can equate it to eating nothing but
broccoli. Sure, it's good for you, but it doesn't supply all the nutrients
that you need to maintain your health.
Supplement bonemeal with well-rotted manure for
an organic alternative or use an inorganic fertilizer such as 6-12-6 or
5-10-5. Side-dress existing bulbs after they have flowered. Don't let
the fertilizer remain on the foliage, or it will damage the tissue.
Q. Could you give me some information about a problem
that I have with my lawn? Patches of dead grass have appeared over the
past few years. I have seeded regularly, but each year I have a few more
than the last year. -- Harley Skirvin, Unionville, Ind.
A. There are lots of possibilities, including grubs,
dollar spot, brown patch, annual grasses dying out and red thread. It
depends on the time and appearance of the patches. It would be best to
bring a sample to the Purdue Extension office in your county for identification,
since so many turf problems have the same symptom of dead patches!
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