Choosing blister rust resistant currants and gooseberries
We all know that non-native plant species can be an issue in the landscape often escaping their bounds and outcompeting resident species, often to the detriment of those already established. In the case of the relationship of currants and gooseberries with blister rust, the edible cultivars weren’t the ones that caused the problem, but their presence allowed it to proliferate.
Bringing Blister Rust to the States
At the turn of the 20th century, with the expansion within the country logging was a huge industry, and the highly sought stands of white pine were some of the most valuable for industry and the railroads. But it was to be dealt a harsh blow. According to the American Phytopathological Society, unbeknownst to the experts at the time, when a shipment of white pine saplings were shipped over from Europe around 1900 to replant an area in the East, the fungus came with them. It landed in the West when they brought in seedlings from France to British Columbia in 1910. Shortly after, the effect to the blister rust rippled throughout the region devastating the pines and causing Ribes spp. to be deemed illegal since they are host plants for the disease.
Symptoms of Blister Rust
Blister rust is the Cronartium ribicola fungus, and although it uses the Ribes spp. as a host, it isn’t a big deal for the currant or gooseberries. Evidence of infection includes tiny, yellow spots on the top of the leaves followed by golden, blistery clusters on the bottom. Sometimes, the infection causes the plant to lose its leaves, but it doesn’t necessarily always kill the plant.
In white pine, cankers form and ooze resin, needles discolor and turn red, and the tree eventually succumbs to the pathogen. When it hit the western United States a century ago it was a big problem for the timber industry, and it continues to be a problem for the native, albeit not commercially harvested, species of white bark and limber pines.
The subalpine and alpine areas of Glacier National Park is where I first learned about blister rust while hiking to the top of Rising Wolf Mountain looking for grizzlies eating the cutworm moths hiding underneath the rocks nearly 30 years ago. Since whitebark pine seeds are also an important food source for the bears, their demise is a concerning turn of events to wildlife experts. There were a lot of dead trees then, and there are a lot more now, although with the dedicated efforts of the Five-Needle Pine restoration efforts, there’s hope that these species will not disappear.
Look for Resistant Varieties
For at least a half-century after the realization that the blister rust was in the United States, gooseberries and currants were banned in much of the country. And, although this is no longer the case in most areas, there are still places (such as Ohio) where it is still illegal to plant the black currant (Ribes nigrum L.) varieties (which are the best ones for culinary uses). But, red currants are fine, as well as gooseberries, as well as hybrids (including hybrids of the black currant) that are resistant to blister rust. Even if you don’t live in an area with prohibitions, it’s smart to choose blister rust resistant varieties. Not only does it prevent your own plants from contracting the disease and reducing your harvest, it takes one piece out of the white pine problem.
It can be difficult to know how our variety choices affect the big picture within our area, but when we know that we can prevent a larger problem, it’s worthwhile to do it. Currants and gooseberries are undoubtedly a delicious addition to the garden. Just look for varieties that are resistant to blister rust so you can grow your best fruit and keep white pine species healthy.