REGARDING CEDAR-APPLE RUST ON
rusts are “alternate host” fungi. The cedar-apple rust switches
between “cedars” (actually junipers) and apple family plants.
Though the orange, jelly-like telial horns we see now on the junipers
are dramatic, they are not harmful to the junipers.
Instead, they are a serious
problem on the crabapples, hawthorns and quince. The rust
creates leaf spots, then leaf drop, and even stem cankers on the
We concentrate our control
measures only on those trees to which it’s harmful. We spray
through leaf development in the spring, usually three times.
Our sprays also control apple
scab, another leaf defoliator of the group.