With the recent drought like conditions a common disease has come to my attention for the Fine Line Buckthorn in particular.
Leaves have been displaying an orange/yellow fungus like substance, which in contrast has caused some leaves to curl. This is called Crown rust, also known as leaf rust. The disease spreads from leaf to leaf as pustules release spores. Under conditions ideal for the disease, new pustules can form in 7 to 10 days. A properly timed fungicide application can provide protection against crown rust. However, spraying should take place at flag leaf emergence. If pustules have already formed on the flag leaf, it is can become tricky to control. Rust diseases typically form on plant leaves when it is too damp, but if it has also been extremely dry the plants may all be under stress which can also cause any plant to become more susceptible to disease. If continued dry periods prolong, water your plants additionally to keep them from stress. Then try a Copper Fungicide or Bonide disease control systemic drench product to see if that helps clear things up. As mentioned, an already existing leaf rust can be tricky to control once present, but with some attention there are hopes of further controlling the spreading of the disease.
