Ribes and White Pine Blister Rust: a second look

         I enjoyed the article by Renee Galeano-Popp in the fall 2016 Aquilegia, but I would like to take exception to her statement that in terms of alternate hosts of gooseberries and currants that “just about any Ribes species will do.”

         Currants and gooseberries have been increasing in popularity among gardeners because their fruits are high in immune-building phytochemicals, because they take up less space than a fruit tree, are easier to pick the fruit, are productive even with late freezes and recent introductions are better flavored and less resistant to diseases.

         According to the American Phytopathological Society, symptoms of White Pine Blister Rust on alternate hosts are orange pustules on the undersides of leaves. I personally have never seen that condition on any of the Ribes at our nursery, nor have I seen that symptom on Ribes aureum or R. cereum in the wild. According to Cornell University, both Ribes aureum and Ribes odoratum and R. odoratum ‘Crandall’ are very resistant to WPBR and in fact both have been used in Canada for breeding resistant varieties of black currant, Ribes nigrum.

         In general, the European Black Currant, R.nigrum is the most susceptible to WPBR, but there are a few resistant varieties: ‘Consort’, ‘Crusader’, Titania’.

         Based on tests in Oregon and Idaho, these varieties are also considered to be the most resistant to WPBR: Gooseberries: Invicta, Jahns Prairie, Poorman, Captivator, Black Velvet, Pixwell; Currants: Rovada, Rondom, White Imperial, Red Lake, Blanca; Gooseberry-Currant crosses: Jostaberry, Orus 10. Ribes ussuriensis is very resistant.

Culturally, White Pine Blister Rust prospers in cool, moist conditions, especially in low-lying areas. So proper watering deeply and infrequently with a mulch to hold moisture while reducing evaporation will help reduce fungal infections of all kinds. Also strengthening the plant with an organic fertilizer and with rock minerals also reduces the chance of fungal diseases. Gooseberries are now only prohibited in 5 eastern states.

One of our favorite resistant Ribes is ‘Gwen’s Buffalo’, a selection of our native Ribes aureum, the Golden Currant.