Western tree large compound leaves bumpy fruitgourd
Tree growers are struggling with the fruit and disease problem, say suppliers
Washington, D.C., August 14, 2017 (USDA news release) —
Rural North America is accustomed to picking the first ripe apples, peaches, apricots and plums of the season. But this year, a crop has yet to be harvested in many regions, including the most populated areas. Dormant orchards in several Midwestern and Southern states and the Northeast are now so bare that some are selling produce at steep discounts.
The agronomist Carl Kornschreck calls the situation a “drought disaster” and he hopes that growers’ efforts at rejuvenation can be avoided.
“We can’t let this happen again,” says Kornschreck, who works with the extension and research service of the University of Maryland.
“This summer is like a glimpse into the future,” he says. “If we don’t develop the next generation of disease-resistant fruit trees, we will lose trees that are currently grown for their fruit quality, yield and resilience to severe frosts and drought,” he says.
Tree growers and regional extension service representatives from all over the country are assessing the current season’s fruit and disease problems to determine strategies for continuing the industry.
Although spring frosts were milder than usual this year in most areas, serious problems were identified this spring and summer, including decline of quality and yield in many commercial andchives. Problems included cankers on fruit bunches, uneven ripening and off-flavors.
“These are serious matters,” says Pete Patterson, Extension for Agriculture and Natural Resources at the University of Minnesota. He and his colleagues were working with an advisory committee of northern fruit growers in his state, who were developing a regionalized strategy to bring a new type of flowering almond tree to their fields.
The tree they selected was Zinnia pulchra, which grows 15 feet high and is tolerant of both drought and late frosts. Growers gave Zinnia one good growing season and then allowed it to mature and flower. Some of those trees have been producing next-year’s crop of nuts and nuts yield already, in one of the first U.S. crops of this crop.
But even with healthy and productive trees, many fruit growers would still like to develop trees that will make good use of limited water, especially when it comes to almonds.
Joe Luttrell, also of the University of Minnesota, is producing “preliminary” studies of Zinnia to determine if it can be useful to fruit growers. One of his studies compared moisture uptake from two-week-old buds, and found that stems from mature trees were 10 percent drier than those of growing-season shoots.
Dry buds are frequently a key symptom of drought stress and Luttrell says his findings support the view that plants exposed to constant drought before they flower and set buds are more vulnerable to extreme drought stress at flowering and fruiting.
Luttrell is trying to identify genes associated with how Zinnia responds to drought stress, but he has a difficult task as he often relies on information from other species. He would like to find the mechanisms used by drought-resistant flowering plants.
“Flowering plants often have special ways of dealing with drought,” he says.
Another study that Patterson is conducting found that broccoli plants produced fewer heads with increasing drought, in part because of a lack of pollen in the flowers.
“It seems that extreme drought