What and when to spray fruit trees

Asked April 29, 2016, 8:17 PM EDT

I have a number of plum, pear, and apple trees as well as fig, hazelnut and apricot, and about 100 feet of grape vines.. All but the apricot appear to be healthy but I was not present for the harvest last year except for some apple and grapes. Most of the apples had evidence of worm. I have been told to spray with lime sulfur after the blooms have fallen (this has happened). I have a well so whatever I spray before the rain ends may end up in my ground water. Do you have any recommendations? My goal is to limit boring insects. I intend to remove the damaged Apricot trees and replace them with apples or pears.

Linn County Oregon fruit trees spray schedule horticulture

1 Response

Hello and thank you for using the Ask an Expert website.You have provided a lot information and raised several questions. First I must say that I can’t recommend sprays for insects until they are identified. There are two at least two different borers that can attack apricot trees and can also attack other fruit trees such as your plum trees. There are also multiple kinds of worms that can infest apples. Remove the damaged trees now get the possibly infected wood off your property or burn the remains while it is still possible this spring. The Lime Sulfur is a spray that addresses fungal diseases not insects. Here is what I recommend. As you find an insect or disease problem on one of your trees bring it in to the MG information desk in your county (Linn). 33630 McFarland Road, Tangent. Phone number is 541-967-3871. I recommend that you call first to ensure that a Master Gardener is on duty. Get the pest/disease identified and find out when and what you need to combat that particular pest. The MG help desk should be able to recommend timing, measures needed, and chemicals (if any) required. In the meantime I have included a link that discusses preventative sprays (and timing) that can be applied to fruit trees. https://catalog.extension.oregonstate.edu/sites/catalog.extension.oregonstate.edu/files/project/pdf/ec631_0.pdf This is a publication that has been put out by Oregon State University Extension Service. Be sure to read the last page of this pamphlet which discusses mandatory spray programs in some counties. Selected counties in the State of Oregon require back yard orchardists to apply preventative sprays to their trees so that diseases and insects are not spread to commercial properties. Linn County is one of those counties, contact the Linn County Extension Office (541-967-3871) to find out what the requirements are.

Finally your concern about anything that you spray will end up in your ground water needs to be addressed. First I recommend that you get your well water tested prior to any spray program you start for your own piece of mind. Second you need to be sure that you follow the instructions on the label of any chemical that you use. The label is the law, you should not use any chemical in a manner that is not listed on the label. Additionally you need to read the precautionary and safety portions of the labels and follow them to the letter. Your well should also be inspected to ensure that it is properly installed and maintained to prevent contamination of any type from entering your well at the well head. Again your County Extension office should have information about this. There are parts of the Willamette Valley that have had the ground water contaminated by nitrates. There are maps that have documented the areas where this is known to have happened. The county extension office can advise you on this subject. Here is a link to the Department of Environmental Quality for the State of Oregon http://www.oregon.gov/deq/WQ/Pages/Groundwater/GWProtection.aspx that addresses groundwater protection. It has many links and addresses protection of groundwater.