Специалисты по садоводству дали советы по борьбе с колючкой и проблемам с урожаем бобовых

Q: You mentioned a mandevilla in a recent column. Mine has gone crazy this year. It’s taken tons of water, though. – Larry K. A: Your mandevilla looks wonderful! This growing season has been a challenge for many of us, with extended heat and drought, so focusing on positive beauty is important. ADVERTISEMENT Mandevilla is one of our own favorite tropical vines, thriving in pots and planters and blooming profusely all summer. It enjoys fertilizer every week or two, and attention to watering, as you’ve done. Mandevilla has become a garden center favorite, with good reason. Being tropical, they are killed by fall frost but are so rewarding until then. Gardeners have options, though. You can let it go and rebuy next year, or you can winter them indoors, keeping them growing in a sunny window as you would a houseplant, returning them outdoors next spring. Thanks for sharing an uplifting photo. Q: My beans have lots of flowers but aren’t setting fruit. I’m watering every three to four days in this drought. A friend says she’s been picking buckets of beans. Help! – Mary G. A: Your watering schedule sounds good, about twice a week during this summer’s heat and drought. If your entire soil mass wasn’t so severely dry, then a good soaking with an inch of water once a week would be enough if rainfall was temporarily short. Your beans producing flowers is an important first step, so that’s a good sign. ADVERTISEMENT String beans do not need bees or other insects for pollination, so we can’t blame a lack of pollinators. Pollen moves inside the flowers naturally without outside help. When temperatures are consistently above 80 to 85 degrees F., however, with warm nights, pollen can become sterile, or flowers can drop prematurely before setting beans. This summer’s extended heat has caused pollination problems on many crops. Why is your friend getting a good crop? Some varieties of string beans are more heat-sensitive than others. Every yard has a unique microclimate that can cause temperature variations. Soil type can affect crop sensitivity, with soil rich in organic material being cooler than heavy clay. What can you do? As long as your beans are flowering, look healthy and are well-hydrated, adding fertilizer likely won’t help the bean set. When temperatures moderate below the 80 to 85 degree mark, pollination will hopefully be successful. Unfortunately, other than waiting for moderate weather, I don’t there’s much you can do to coax the bean plants to produce. Q: Since several homeowners in my neighborhood do not control weeds in their lawns, thistles are multiplying in this drought. I’ve learned that they colonize and I’m afraid they will get a foothold in my yard. I have enough trouble fighting crab grass! – Mary B. A: Canada thistle has thrived in this year’s heat and drought. In my opinion, it’s one of the nastiest weeds around. ADVERTISEMENT It flourishes when our lawns and landscapes are stressed because its root system can extend 15 feet deep and the roots of a single thistle plant can spread outward 18 feet. They rob moisture from surrounding lawns or plants and drain soil nutrients. Canada thistle is also allelopathic, which means that its root system secretes chemicals that are toxic to surrounding vegetation. It exudes these toxins as a way to diminish other plants, so it can spread easier with less competition. Canada thistle can quickly colonize an area, so your concern is well-founded, Mary. And it certainly doesn’t respect neighboring property boundaries. There isn’t a practical way to preemptively stop your neighbor’s thistles from creeping into your yard. Because they’re spreading primarily from underground rhizomes, rather than by seed, pre-emergent type herbicides won’t create a barrier to rhizome spread. The best control will be vigilance. If and when you see small thistles popping up in your lawn, be prepared. Lawn herbicides with the active ingredient triclopyr can be effective without harming the lawn, when label directions are followed. Fall can be a successful time for applying herbicide when thistles are carrying nutrients to their roots for winter storage. Herbicides can also be applied in spring when thistles are actively growing. Although farm-type herbicides can be effective for thistle control, many such products specifically indicate they are not to be used on residential lawns. ADVERTISEMENT If you have a gardening or lawn care question, email Don Kinzler, NDSU Extension-Cass County, at [email protected]. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.