HERSHEY, Pa. — Just as babies are not born with an instruction manual, guidelines for replacing maturing raspberry and blackberry plantings do not grow on berry canes.
In the absence of such a shortcut, Marvin Pritts, a Cornell University plant science professor, told bramble growers Jan. 27 what maladies he thinks are worth fighting and which ones signal it is time to give up on a planting.
Pritts spoke at the Hershey Lodge during the annual meeting of the North American Raspberry and Blackberry Association, or NARBA, held this year in conjunction with the Mid-Atlantic Fruit and Vegetable Convention.
Ideally, farmers could just track their costs of production and replace the brambles when old age dropped their yields to unprofitable levels, he said.
“In my experience, a lot of growers don’t really have a good sense of that,” he said.
Production also varies greatly from year to year, which can make tearing out a planting a tough call even for meticulous bookkeepers. A stand may be unprofitable one year, but profitable again the next based on weather, nutrients and other factors, he said.
Instead of making a mathematical calculation, Pritts said growers should evaluate the nature of the plants’ problems to decide if the stand is worth trying to save.
Viruses, for instance, are a “no hope” situation, he said. Mosaic virus, characterized by discolored leaves and crinkling, is transmitted by aphids and leafhoppers. Even if the farmer nurtures the existing canes, the new ones will also be infected with the virus, he said.
Some viruses, like tomato ring spot virus, are incurable anyway, he said.
Glyphosate injury also generally means the end for a bramble patch. Accidental spray drift can occur even if the applicator is careful, and the plants just do not recover well from it, Pritts said.
Damage from pre-emergent herbicides is often not ruinous, however. Berry plants can often outgrow minimal bleaching, especially if farmers give the plants the proper attention, he said.
Root rots like phytophthora and verticillium wilt spell doom. “Boy, it’s hard for me to imagine that plant recovering,” he said.
Because phytophthora can last in the soil for a very long time, raised beds are the safest way to replant that land, he said.
Besides bringing in clean soil, raised beds can drain better than the regular ground, leaving less moisture available for phytophthora to take hold, he said.
Canes can typically survive winter damage. If the floricanes, or fruit-producing canes, die, the primocanes, or first-year shoots, should still be OK next year, he said.
The temperature of lethal cold varies widely. Tender cultivars might be hurt at zero, while heartier plants can tolerate cold down to minus 10 or minus 20, he said.
If cane borers or rodents girdle the canes, the farmer can simply prune out the damaged canes. “It takes some effort,” but the planting can be saved, he said.
Cane diseases such as spur blight or cane blight can be remedied with lime sulfur and pruning, he said.
Fire blight and tip disease can be fixed with pruning and pinching. “Those aren’t fatal,” he said.
Berry plants can live for a few years after damage from crown-boring insects, but the canes come up weak and may not be much good, Pritts said.
The plants will survive, though, if the fruit gets damaged by tarnished plant bug or sun scald, he said.
Mildews, leaf spot and gray mold are moisture- and weather-dependent. “That’s really no problem,” and there is no reason to wreck a planting over one wet year, he said.
Rust is a bit trickier. Late leaf yellow rust can get on the fruit, but it is manageable.
Orange rust shows up in the spring on black raspberries and blackberries. It leads to spindly primocanes and is systemic. It can occasionally be handled with fungicide, but in most cases farmers should just start over, he said.
Red raspberries are somewhat immune to orange rust and other black raspberry diseases, he said. Decades ago experts warned of planting red raspberries too near their bramble cousins, but that is not such a concern now that new plants can be considered clean, he said.
In addition to hosting speaker panels during the convention week, the raspberry and blackberry association also handed out its third Research or Grower Award.
Nathan Millburn, the association president, described award recipient Nate Nourse of Nourse Farms in South Deerfield, Mass., as “a very good, close personal friend.”
Nourse is the sales director at the company, which Millburn described as a leading plant supplier. Nate Nourse’s father, Tim Nourse, bought the business in 1968.
Nate Nourse has been heavily involved in NARBA, Millburn said. Nourse Farms was a sponsor of the NARBA conference, and Nourse served as New England’s NARBA representative from 2006 to 2010. He was the president of the organization from 2010 to 2011 after spending a year as vice president.
Nourse also helped start the North American Bramble Growers Research Foundation, the research arm of NARBA.
Nourse got the idea from the North American Strawberry Growers Association, Millburn said.
Nourse served as president of the strawberry association in 2009 and 2010, according to the group’s website.
“NARBA is a very important part of the raspberry world. There is a lot more benefit that they deliver than people realize. The camaraderie of the association is one of the best that I have ever been involved in,” Nourse said.