These become clear with age and may run together to form larger spots. Affected leaves may shed prematurely. Chemical control may be only partially effective. This problem can be prevented by using nematode-free planting stock and a sterilized potting medium. In severe cases, foliage turns yellow and dies.
Alternate host is pine where it produces a blister rust on the needles.
Use rust resistant varieties when available. Fungicides should be used at the first sign of disease and continued on a 7-14 day schedule. First symptoms are observed as a yellowing or chlorotic appearance along the veins of young leaves. As the chlorosis becomes severe, defoliation occurs. Affected plants do not wilt or die, but have a spindly type growth which detracts from the plants overall appearance.