‘Paul’s Scarlet’ hawthorn trees produce deep-pink double flowers in the spring but can be bare by midsummer, victims of leaf blight. The good news is there are plenty other varieties of hawthorn trees you can plant.

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In the Garden

Q: We recently moved into a house with a hawthorn tree in the front yard. The tree had beautiful red blooms in spring, but now it has developed unsightly black spots on the leaves. Is there a way to prevent this?

A: Your tree is undoubtedly ‘Paul’s Scarlet’ hawthorn (Crataegus laevigata ‘Paul’s Scarlet’). This hawthorn sports gorgeous clusters of deep-pink double flowers in spring.

Unfortunately, it’s highly susceptible to a fungus disease known as hawthorn leaf blight. The first symptom is spotting on the leaves. The disease won’t kill your tree, but it will cause it to drop its leaves, and by midsummer you’ll be stuck with a bare tree until next spring. Fungicides labeled to help control this disease are rarely successful, and the leaf-dropping will occur every year.

Gardening Events

Ciscoe’s Picks

Heronswood Garden Summer Open & Plant Sale:

10 a.m. to 4 p.m. Saturday, July 23. Plant sale and lectures by Dan Hinkley and Sam Decker (free) and self-guided garden tours ($10 donation). Address: 7530 N.E. 288th St., Kingston.

heronswoodgarden.org

Molbak’s Share Your Harvest:

Every Sunday (9 a.m. to 6 p.m.), through Sept. 18. Bring your fresh-picked fruit, veggies and herbs, and Molbak’s will coordinate delivery to Hopelink’s food banks. No need to pre-wash. Address: 13625 N.E. 175th St., Woodinville.

molbaks.com

Magnuson Children’s Garden Family Days:

6:30 p.m. to 8 p.m. Tuesday, July 26. Family-friendly activities in the Children’s Garden with a Beatles tribute band, Creme Tangerine, in the amphitheater next door. Free. Address: Amphitheater and Children’s Garden, inside the Community Garden, at Magnuson Park, 6344 N.E. 74th St., Seattle.

magnusonnatureprograms.com

Fortunately, if you like hawthorns, there are plenty of attractive disease-free replacements.

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Lavalle hawthorn (Crataegus x lavallei) develops a rounded habit and usually grows to about 20 feet tall. The clusters of spring flowers are white, followed by showy, brick-red fruit, and glorious coppery red fall color. The Washington hawthorn (Crataegus phaenopyrum) also sports attractive white flowers. It grows to about 25 feet with glossy red berries, and the leaves turn brilliant scarlet-purple in autumn.

If you’re hooked on red flowers, the English hawthorn ‘Crimson Cloud’ (Crataegus laevigata ‘Crimson Cloud’) is resistant to the disease and offers fiery clusters of single red flowers starred with white centers, followed by small red fruit. Replace it in fall while it is unattractive; however, if you are a superstitious sort, you better wait until spring. According to Gaelic and Irish folklore it’s very unlucky to cut down a hawthorn tree at any time other than when it is in full bloom.

Q: Please tell me how to kill poplar stumps. I cut the trees down because they were sending up suckers, and now they’re putting up twice as many shoots and they’re coming up all over my yard.

A: Poplars are famous for suckering, and the problem only gets worse if you cut them down. The reason they continue to sucker is because cutting down the tree doesn’t kill the roots, which then send up suckers to produce the food necessary to keep them alive.

In theory, if you cut off every sucker right as they emerge before they develop enough foliage to produce food, it would starve the roots and cause them to die off. Unfortunately, that could take years, and it takes only a few missed suckers to keep the cycle going.

Hence, this is one case where it’s usually necessary to resort to using a chemical herbicide to solve the problem.

Begin by mixing a systemic herbicide containing glysophate (such as Roundup) in a disposable container at the concentration indicated on the label for killing stumps and suckers. Then cut the stumps close to ground level, and immediately use a sponge paint brush to cover the entire surface of the stump with the herbicide, making sure to thoroughly cover the outside edges.

The herbicide will be absorbed and will kill the roots directly under the stumps. It won’t kill the ones farther out, however, and you’ll need to do the same thing to the suckers.

Follow-up treatments might be required if a new set of shoots appears, but if you stick with it, eventually the last of the underground roots will die off and the suckering will end. Follow all safety conditions on the label, and remember that glysophate will kill most anything it hits, so use caution when working near valued plants. Most important, consult a nursery professional to help you choose a replacement tree that doesn’t have a tendency to sucker.