More people than ever are gardening during the pandemic and you’re bound to have questions. Turn to Ask an Expert, an online question-and-answer tool from Oregon State University’s Extension Service. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. To ask a question, simply go to the OSU Extension website and type in a question and the county where you live. Here are some questions asked by other gardeners. What’s yours?

Q: I have espaliered Gala apple trees. Some of the fruit has brown spots. What is this? Can it be treated? What is the treatment? – Yamhill County

A: Apples are prey to many types of fungal diseases, along with apple maggot (the worm inside the apples) and also codling moth (another worm inside the apple). Some of the diseases are fungal, others bacterial or viral.

This looks like apple scab, a fungal disease. Spores are everywhere and your best protection are organic sprays. The solution is a program of sprays that will take care of insect pests as well as your fungal issues. First dispose of the apples that are infected in the garbage, also take off any leaves that look infected; throw them in the garbage. If you compost any of your waste make sure you do not put diseased leaves, twigs, fruit or other material that is diseased in the compost unless you know you can bring the heat up to about 165 degrees.

Keep your soil free of these apples and leaves as well as weeds. Add about 2 shovels full of compost around the trees and water the soil, not the trees. No overhead watering. Moisture increases the growth of fungus. Also, make sure there is plenty of airflow through your espaliered trees. Prune lightly.

The two sprays that I use most often are a lime/sulfur spray and neem oil (pure neem not mixed with anything else – find it on online). Both have oil in them and will smother insect eggs and kill any insects they touch but they will also kill the fungal spores. Lime/sulfur spray can be found at Wilco and Coastal stores. Follow the directions and wear protective gear when spraying. It is a large container but it will last – store in a cool, dry and dark place. Some of the sprays will congeal. If that happens place the container (sealed) in a bucket warm water until it returns to liquid form.

A program or schedule of spraying will help you keep your apple trees healthy. November through February spray at least once with a dormant oil, March and April spray each month for scab and mildew with lime sulfur (temperature should be over 40 degrees and not above 85 degrees). Wait at least 10 days and spray with neem and insecticidal soap (they can be mixed — add liquid soap to the neem oil 1 tablespoon per 1 gallon of water).

Just before the blossoms open, spray with lime sulfur. Do not mix lime sulfur with anything. Spray insecticidal soap for bugs. Make your own with 1 tablespoon of liquid soap, 1 tablespoon of vegetable oil to 1 gallon of water. DO NOT SPRAY when blossoms are open. Every spray I mentioned will kill or harm pollinators.

After the fruit has set the pollinators will not be around. Spray again with lime sulfur. You can also wait 10 days and spray with neem. The reason we use two sprays is because they come from different categories scientifically. It means they attack the fungus in different ways.

After you harvest your apples if you still have a problem, spray a mixture called Bordeaux. This will help stop the fungal growth as well.

All of these sprays have instructions, please follow them to the letter for your safety and the health of your trees. This may seem like a lot but, it works and you will have better tasting apples. You may also want to apply agricultural lime to the soil if you have not done so. There is another physiological problem called apple cork. Applying lime to the soil will help with this issue.

You can purchase an inexpensive pH test kit at local nurseries. Test the soil for a pH. If it reads around 6.0 or lower you can add the lime. Lime raises the pH of the soil. Apples like a pH around 6.5. Here is a link to an article regarding this disorder.

I am also putting a link to a rather long article with info on growing apples and their diseases. Again, while this may seem like a lot of work, once you have the materials and a schedule it isn't and will give you great apples.

One last thought, spraying requires a windless day over 40 degrees and dry for at least eight hours after you spray. That is sometimes hard to find in the fall and early winter but there are a few days when the conditions will be right. Good luck with your beautiful espaliered trees. – Sheryl Casteen, OSU Extension Master Gardener

Can’t identify the spots on cherry leaves? Ask an expert

Q: My cherry tree has developed some strange markings on some of its leaves. What sort of disease or pest is it? Also, where can I get more information on the pests and diseases of fruit trees in the Pacific Northwest? – Washington County

A: Nice images that tell me you have something called cherry leaf spot. Although there are a lot of leaf spots on cherries, that is the real name we use for this fungal disease. The spots stay small and purple but have white sporulation on the underside of the leaf. You can read all about it here. You also might like this publication. – Jay W. Pscheidt, OSU Extension plant pathologist

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