NDSU Yard & Garden Report for July 23, 2018
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North Dakota State University Extension YARD & && GARDEN REPORT July 23, 2018 Vol. 6, No. 3 Tree-Eating Sharks It’s Shark Week in America. All week we can watch horror stories of people getting attacked by sharks: Rodney Fox was attacked by a great white shark in Australia. He recalled, “I’m looking through the pink of the water, through my own blood, and … I see the head. Getting bigger.” The shark bit into Rodney, ripping open his body, crushing his ribs and puncturing his lungs. Rodney required 462 stitches to seal his wounds. Ouch! Bethany Hamilton was surfing one day in Hawaii. Before she knew it, her arm was ripped off by a tiger shark. She said, “It was about a two- to three-second period and when it ... was attacking me all I saw was like a gray blur.” Are you scared yet? Imagine YOURSELF in a swimming pool. A trap door in the pool opens and a shark is released. The shark comes Mowers terrorize trees by scraping their trunks (left) and shallow roots (right). toward YOU… you can hear the water ripple as it swims … it’s rushing The mower is one of the leading toward YOU… and you are helpless! killers of trees in North Dakota. Inside This Issue This is the way a tree feels when a Mowers attack bark, the armor of w Tree-Eating Sharks 1 lawn mower comes near. Absolutely a tree. Just beneath the bark is the helpless! phloem, a precious layer where nutri- w Buying Ladybugs 2 ents are carried from the leaves to the Every time you start your mower, w Plant Health Care roots. If you expose the bark, the every tree in your yard shudders in phloem is destroyed. If you destroy w Vegetables, Fruits 3 fear. Your mower—a machine the phloem, the roots stop receiving w Woodies, Flowers, Lawns 4 designed to bite through plants with a nutrients from leaves. The roots sharpened steel blade—will soon be w Weather Almanac 5 starve and die. brushing against the tree’s skin. (continued on next page) You Can’t Buy Friendship Ladybugs are a gardener’s best friend. The problem with buying They serve the role as the “Garden ladybeetles is the insects still think Sheriff,” killing all the bad bugs that they are in the mountains. They have threaten our plants. They do a great an inborn desire after hibernating to job of keeping law and order in the fly several miles down to the lowland garden. A ladybug (more properly valley before they begin feeding again. called a ladybeetle) can eat as many as Studies have shown that purchased 5,000 aphids in its lifetime! ladybeetles generally fly 20–30 miles Although they are a great friend in after being released, burning up their the garden, don’t buy ladybeetles. fat layer before starting to eat new insects. Within 24 hours, less than 1% The most commonly sold lady- of the ladybeetles you release in your beetle is the convergent ladybeetle. garden will remain—maybe these These beetles eat heartily during ladybeetles have broken wings. Within autumn in the lowland valleys of the need to have pests in your garden for 48 hours, you will have difficulty Western USA, develop a fat layer in the predators to eat. Instead of finding any ladybeetles. For goodness their bodies, and then fly up nearby buying ladybeetles, focus on keeping sake, gardens in the next county may mountains to hibernate. These beetles your plants strong so they can benefit more than your garden from sleep together in huge clusters of up withstand minor pest infestations. these ladybeetles! to 40 million. While sleeping, these Short-lived and relatively safe insecti- ladybeetles are gathered, refrigerated In general, buying predator insects cides such as neem, spinosad, BT and and then packaged for sale. has its limitations, especially since you soaps are available when needed. Tree-Eating Sharks (continued) If that isn’t bad enough, the at least 3 feet in diameter around the well as creating excessive heat stress in wounds created by mowers are easily tree—even more is better. The mulch summer. Rock mulch compacts the invaded by diseases. should be 3 inches deep. Keep mulch soil and provides no nutrients. to a minimum for the first 3 inches How much damage to the bark What are you waiting for? The away from the trunk. Heaping mulch can a tree withstand? next shark attack is coming soon! against the trunk can create stem rot Trees generally survive if the and provide nesting habitat for voles. damage is limited to 25% or less of Use wood-based mulches such as the bark around the tree. As damage chips or shredded bark. This mulch levels increase higher, the tree suffers will conserve moisture, smother higher levels of decay and dieback. If weeds and enrich the soil. Wood the bark is stripped around the entire mulch will insulate tree roots, keeping tree, it will die. This is called girdling. them cooler in summer and warmer If you love your trees, protect in winter. Most importantly, the them against your terrorizing lawn mulch will protect the tree from your mower (and string trimmer). mower! Place a ring of mulch around each Rock mulch is less desirable. It tree. Follow the “3-3-3 rule” (see traps heat, accelerating bud break (and photo). Place a ring of mulch that is potential frost injury) in spring, as A properly mulched tree. 2 NDSU Yard & Garden Report July 23, 2018 Plant Health Care Vegetables Early Blight on Tomato Bacterial Speck, Spot Sunscald on Pepper Avoid overhead watering. Remove Dark, corky, sometimes raised spots Pepper and tomato fruits exposed to infected foliage. Protect with develop on green and red fruits. Spots the direct rays of the sun during hot chlorothalonil, mancozeb or copper. develop on vines. Avoid working in the weather will burn. This occurs on Stake and prune vines. Sow blight- garden and wounding vines when wet. plants with sparse foliage. Fertilize and resistant varieties in the future. Spray with copper to prevent spread. irrigate to promote healthy plants. Male Female Prevent Potato Scab Potato Cracking Fruitless Flowers Scabs form on expanding tubers after Tubers may crack due to a lack of Most flowers on cucumber and squash vines begin to bloom. Keep soil moist water, excess heat, chemical injury, or a vines are male (left photo) and do not for the next month. Avoid fresh manure rapid burst of growth caused by an set fruit. They provide pollen to fertilize and susceptible cultivars (Red Pontiac, application of fertilizer or a major female flowers (right photo; note the Kennebec, Yukon Gold) in the future. rainfall. Maintain uniform soil moisture. fruit attached). Use insecticides judiciously to promote bee activity. Fruits Fire Blight on Pear Leaf Spot on Cherry Rust on Juneberry Branch tips wilt and darken. Prune tips Leaves develop spots and drop. Rake Berries develop “spikes” that emit going 8 or more inches into symptom- leaves to remove fungus. Prevent spores. This rust comes from junipers. less wood, leaving a stub of at least 4 infection next year using a spray of Avoid planting near junipers. Prune to inches. Sterilize pruners between cuts. fungicide at 90% petal fall, followed by reduce shade and humidity in canopy. Paint “ugly stubs” and prune in winter. two sprays at 10–14 day intervals. Use fungicides when shrubs set fruits. July 23, 2018 NDSU Yard & Garden Report 3 Plant Health Care Trees and Shrubs Ash Flower Gall Wooly Oak Gall “Tumors” develop after mites bite into Fuzzy balls appear, especially on leaf male flowers in spring. These galls may midribs. Inside is a developing wasp. turn brown and persist through winter. The gall will drop off and an adult wasp These galls are harmless; no treatments will emerge. These galls are virtually are needed. harmless and no treatments are needed. Lightning Damage Bark Shedding Lecanium Scale Some or the entire tree suddenly turns This is natural. The bark of a tree Insects under shells suck sap, causing brown and dies. A strip of bark may be darkens, hardens and dies over time. thin and dying branches. Crawlers are burned or missing along the entire tree, New growth and new layers of bark are hatching now. Spray with carbaryl, top to bottom. Remove loosened bark. created beneath the old bark. As the pyrethroids or summer oils. Suffocate Irrigate during dry spells. Remove girth of a tree expands over time, the with dormant oil in early spring. severely damaged trees. new layers push out the hardened old Flowers bark, which cracks or peels off. Lawns Measles on Peony Mildew on Sunflower Dull Mower Blade Red spots and blotches appear. Avoid Plants are stunted with yellowing along Dull mower blades will shred, not cut overhead sprinkling. Remove leaves and leaf veins. Fungus is inside the plant grass leaves. Damaged plants will be stems this fall. Fungicides may be and no sprays are useful. Pull out more susceptible to injuries and grow sprayed when plants are 4–6 inches tall plants. Remove wild sunflowers in slower. Sharpen blades or replace every next spring. vicinity. Use resistant varieties. year; more often if necessary. 4 NDSU Yard & Garden Report July 23, 2018 Weather Almanac for July 16–July 22, 2018 TEMPERATURE1 RAINFALL1,4 GROWING DEGREE DAYS1,5 July 16–22 July 16–22 2018 July 16–22 2018 Site Avg Norm Max Min Total Norm Total Norm Total Norm Total Norm Bottineau 66 68 85 45 0.30 0.55 8.13 9.23 102 113 1294 1071 Bowman 69 70 89 52 0.07 0.49 9.51 8.39 108 126 1202 1054 Carrington 67 70 83 50 0.08 0.75 8.46 10.28 107 126 1409 1166 Crosby 68 67 88 50 0.13 0.62 7.49 8.15 114 106 1262 973 Dickinson 70 70 90 50 0.69 0.56 9.41 9.24 117 120 1327 1058 Fargo 70 71 83 50 0.88 0.59 9.65 10.20 121 132 1598 1262 Grafton 67 68 86 45 1.42 0.55 9.96