by Lis Friemoth
Prepare now for application of dormant oil on fruit
trees
Whether you are an accomplished home orchardist, a newbie
or a wannabe, some interesting pests will cross your
path on the quest to grow quality fruit. As your abilities
grow and develop, so will the care plan that works in
your individual space and with your chosen fruits.
Each season of each year brings challenges and tasks
that need constant monitoring, evaluation and adjustment.
Now is the time to evaluate the successes and challenges
of the past growing season.
One of the greatest challenges facing any orchard are
insect pests. Some years can present the unusual infestations;
last year it was Magicicada septendecim (the 17-year
Cicada). Some pests arrive like clockwork, like Japanese
beetles. They hit every year in varying degrees of severity
and are usually at their most annoying when the fruit
is luscious and ripening. But there are some common fruit-crop
pests that have a quiet presence, only reaching a treatable
stage when the populations are at relatively high levels.
If these are not monitored regularly, treatment is often
reactive rather than proactive.
Being proactive can include a plan for a dormant oil
application to nip some of those critter populations
in the bud. Starting the season off with a dormant spray
is a low-toxicity method of lessening growing-season
pest maintenance. Aphids (many species), Cacopsylla pyricola
(Pear psylla), Panonychus ulmi (European Red Mite), and
Quadraspidiotus pericosus (San Jose scale) are some of
the common fruit crop pests that can be reined in with
an appropriately timed oil application. Do keep in mind
that each plant has particular pests that love it. Understanding
the life cycle of each pest will help you to find the
most vulnerable point in that critters life — which is
often the best time to treat. Successful treatment includes
choosing the appropriate formulation based on plant type,
insect pest and time of the year.
What type of oil is best to use? There are a few different
brands that can be found at most major stores. As long
as they are horticultural products that are formulated
for your particular crop, pest and timing of application,
the choice is up to you. Be sure to read the label carefully.
It will tell you everything you need to know and then
some.
What is in a dormant oil product? The components are
relatively common: refined mineral oil, soap, and water.
Do not consider that a recipe. I DO NOT recommend this
as a do-it-yourself project. The oils and soaps used
in commercial horticultural products have been specially
formulated for safe plant use and consistency. This ensures
that the products you purchase will work the same way
every time and when used appropriately will result in
minimal damage from sun exposure or suffocation. Using
household products may be good for the house but will
spell trouble — or death — for plant material.
How does dormant oil work? Depending on the pest, the
oil when applied well, will either suffocate it or render
the feeding mechanisms useless. Seems heartless, but
that’s life and death in the plant world.
When and how is dormant oil applied? You should be planning
now to be ready. The treatment time is optimal as temperatures
get to and stay above about 40 F and below 70 F. There
will be days that reach 40 and drop back down, but be
patient and wait for a true warm-up.
Warm spring weather brings the over-wintering pests
out of dormancy. Once they are respirating, suffocation
via oil coverage will be much easier. Avoid applications
after the new buds open beyond a 1/4-inch of green. This
has the potential for bud damage and subsequent fruit
loss.
In order to get good coverage, especially in larger
trees, a pressure sprayer should be used. This is not
a piece of equipment that most backyard orchardists have
on hand. Be smart, don’t try to rig ladders and hoses
and chairs and masks and gloves and belts and whatever
else together to make your small sprayer do the job.
There are licensed applicators out there that will gladly
do the application for you. A hospital stay is much more
expensive than the sprayer dude or dudette.
— Lis Friemoth is a horticulture diagnostician. Contact her at (262) 745-2904, P.O. Box 58, Springfield, WI 53176, visit online at www.thegardenhoe.com or e-mail her at gardenhoe@tds.net. Listen to Liz from 9 a.m. to 10 a.m. every third Saturday on WISN AM1130 radio. |
