Hello – Thank you for reading my question. I have three limeglow junipers in a bed of lamb’s ear (Zone 6, part sun, average to dry soil) and I like them very much. I’ve just realized, however, they could be a potential host to rust as they’re not noted as resistant like my japanese garden juniper or blue star juniper (University of Minnesota Extension). I bought them before learning about cedar rust. We have an apple, crabapple and serviceberry tree that deal with rust every summer (we are considering spraying next winter). Should I dig up the three limeglows? (The crabapple and serviceberry are right behind the limeglow but separated by some gold ninebark.) There are some eastern red cedar nearby so I’m wondering if chucking my three limeglows would be a waste. I do want to help the trees. Thank you for your time.
Hello – As you are familiar with cedar-apple rust, you know that this fungus disease requires two different plant families to complete it’s life cycle: one plant from the Cupressaceae family (red cedar, juniper) and the other from the Rosaceae family (apple, crabapple, serviceberry etc.). It is advisable to not plant these families within a few hundred yards of each other. As noted, you have plants from both of these families in your garden.
While there are rust resistant varieties of juniper available, unfortunately, Lime Glow (which is a beautiful conifer) is not among them. I’m including a link below to an article which discusses the creeping juniper species (Juniperus horizontalis) and it’s cultivars including Lime Glow.
You mentioned the University of Minnesota Extension so I searched their site for information on Japanese garden juniper (Juniperus procumbens) and blue star juniper (Juniperus squamata ‘Blue Star’) in order to confirm these species were resistant to cedar-apple rust. I found no mention of them on the site. (Click here to access the article I referenced.) However, on other sites I did find information that japanese garden juniper (Juniperus procumbens) is resistant and blue star juniper (Juniperus squamata ‘ Blue Star’) is not. I’ve include the links to both articles below.
So you’ll have some decisions to make. The eastern red cedar, blue star and the lime glows are all host plants for cedar-apple rust. You’ve noted that the Lime Glows are very close to the crabapple and serviceberry but I don’t know the location of the others. I’d deal with the host plants before resorting to spraying. Good luck!