Unfortunately, there are no environmentally friendly sprays to combat Pacific Coast pear rust or trellis rust on pear trees. The best option is to remove affected leaves and twigs to try to limit the severity of the disease.

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In the Garden

Q: Is there an environmentally friendly way to prevent rust on my pear trees?

A: Pear rust has become a major problem in our region the past few years. The fungus disease can be easily identified by bright yellow to orange spots that form on leaves, twigs, branches and fruit.

There are two rusts affecting pears in our area. The symptoms of Pacific Coast pear rust usually show up soon after flowering is over. Yellowish spots appear on developing fruit, which become malformed and often drop from the tree. In severe cases, the yellow spots also form on leaves and twigs. In addition to pears, this disease also affects hawthorn, apple, crabapple, serviceberry, quince and mountain ash.

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Ciscoe’s Picks

Sequim Lavender Weekend

July 17-19. 9 a.m. to 7 p.m. Friday and Saturday; 9 a.m. to 5 p.m. Sunday. Live music, arts and crafts at the street fair. Many farms on tour (hours and admission vary by farm). Phone: 360-683-6197.

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Music in the Garden, Bellevue Botanical Garden:

5:30 p.m., Saturday, July 18. Pack a picnic dinner, bring a blanket and enjoy Summer Pops with Brass Band Northwest. Free. 12001 Main St., Bellevue.

bellevuebotanical.org

21st annual West Seattle Garden Tour:

9 a.m. to 5 p.m., Sunday, July 19. Nine beautiful residential gardens. Phil Wood, landscape designer, will give the lunchtime lecture. Admission: $20, under age 12 free.

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Trellis rust is identifiable by bright yellow or orange spots that are evident on both surfaces of the leaves. The spots also can show up on twigs, branches and fruit. Often, heavily infected fruit mummify in place rather than falling from the tree.

 

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Over three feverish days, Bob Lilly and his team of Arboretum Foundation volunteers struggle to transform their plot inside the Washington State Convention Center into an award-winning garden. Read more. (Lauren Frohne / The Seattle Times)    

Both of these diseases require an alternate host within about a 1,000-foot radius for the disease to occur. The alternate host of Pacific Coast pear rust is a conifer species, incense cedar (Calocedrus decurrens). The alternate host for trellis rust is juniper.

There are no chemical sprays registered for homeowner use that will control pear rust, and the only truly effective control is removal of the alternate host. Obviously that isn’t likely to happen if you live in a heavily populated urban setting. Hence, the only option left is to remove affected leaves and twigs to try to limit the severity of the disease. Then keep your fingers crossed that someone will come up with an environmentally friendly spray that will prevent the disease in the near future.

Q: Is it true that citrus peels will keep cats out of my garden?

A: There’s nothing worse than when a cat decides to use your garden for a litter box, especially if it’s your vegetable garden. From many comments I’ve received, it appears the often-recommended use of citrus peels is rarely, if ever, successful.

The majority of commercial deterrents haven’t proved to be very reliable, either. If you decide to try one, check the label. Not all of them are suitable for use in a veggie garden. Moth balls, also often recommended, should never be used because they contain toxic substances inappropriate for use around edible plants, and are attractive to children who think they are candy.

Fortunately there are two methods that really do work. The first is to pound 8-inch-long sticks or bamboo stakes into the soil at 4-inch intervals. You need to get them deep enough into the ground so the cat can’t easily knock them down. If there isn’t room to scratch, the cat will look for another area with open unencumbered soil. The obvious disadvantage to this method is that it takes forever to pound in all those stakes, and they’re a pain to work around.

The other method is more expensive, but much less intrusive. Battery operated devices exist that attach to your hose and contain heat and motion detectors. When the device detects an intruder, it blasts it with a powerful spray of water, reloads and gets ready to fire again. I’ve used one successfully to prevent raccoons from getting into and tearing up my fountains. The key is to place them where they have a sight line into most areas of the garden, yet don’t look directly into the sun. If you have a large garden, more than one might be needed. By the way, if your significant other is a gardener, don’t forget to tell him or her these devices are out there. If you hear a “yeeeeow,” instead of a “meeeeow,” your spouse probably just got a big surprise!