Q: Our dwarf Colorado blue spruce is no longer dwarf. It's nearly five feet tall and probably just as wide. Can it be trimmed? If so, when is the best time to do this? - Shirley Smedshammer, Fargo.
A: There are several dwarf varieties of Colorado blue spruce (Picea pungens.) They stay relatively short compared to the 40-feet-tall parent, only growing a few inches every year. But the dwarf varieties can still become a large, mound-shaped plant, eventually reaching a height of 5 to 6 feet. Several newer varieties remain shorter.
Your dwarf spruce might be close to its maximum height. To be sure it gets no taller, its dimensions can be held at their current size by "mold-and-hold" type pruning, in which you prune the outer tips each year in May or June. But if you want to decrease the spruce's current size, it's important to limit pruning to the vicinity of healthy needles. If cuts are made back to bare twigs, growth will not usually sprout. The spruce can be shortened somewhat, just don't go back too far into old wood.
Q: My honey crisp apple tree started to produce well last summer. The problem is that the apples looked nice on the outside but had brown streaks on the inside. Are these edible and what can I do to prevent it this year? - Marlene Olson, Fargo.
A: Brown streaking inside apple fruits is usually caused by the apple maggot. Adult flies emerge from the soil in late June or early July. Females puncture developing fruit to lay eggs, which often leaves a tiny dimple. The eggs hatch into small wormlike maggots, which tunnel through the fruit as they eat, causing brown streaks. By late summer, maggots exit the apples, enter the ground to overwinter, and the cycle starts again the next year. Fruits are safe to eat, and the maggots have usually left by the time apples are ripe.
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To control apple maggots, spray trees with Sevin or spinosad insecticides beginning about June 25, and continuing at seven- to 10-day intervals until mid-August. Sanitation is important. Remove all fallen apples immediately to prevent maggots from entering the soil for future infections.
There's one other problem that Honeycrisp growers encounter causing internal brown spots. It's called bitter pit, and is more common on younger, newly fruiting Honeycrisp trees. It's a physiological disorder caused by interactions of growth conditions, fertility and vigor. Commercial Honeycrisp growers often apply calcium sprays. But if the internal browning is in railroad-like streaks, apple maggot is the more common problem.
Q: Is it possible to start Korean lilacs from the suckers growing up around the shrub? - Shirley Smedshammer, Fargo.
A: Suckers don't pop up out of the ground around the perimeter of dwarf Korean lilac the way they do in old-fashioned common lilacs. But sometimes there are sucker shoots close to the base of Korean lilacs that can be separated from the mother plant, as long as the sucker sprout has its own little root system. It might be necessary to cut adjoining woody tissue to separate the sucker. Early spring is best. Take extra care to get moist soil immediately around the roots if doing the operation now, when lilacs are in full leaf.
If you have a gardening or lawn care question, email Don Kinzler at ForumGrowingTogether@hotmail.com . All questions will be answered, and those with broad appeal may be published, so please include your name, city and state for appropriate advice.
