In general, plants look healthy now. Here are some specific diseases we have seen at the clinic.
Anthracnose of shade trees requires cool, wet conditions the 2 weeks after budbreak. As many sycamores, oaks, maples, and ash trees susceptible to anthracnose opened in warm, dry weather, anthrac-nose may be sparse. Reports of ash and sycamore anthracnose are coming from wetter areas. Slow to leaf out, sycamores appear to have the bud blast stage of anthracnose. As a reminder, fungicides are not recommended for anthracnose of shade trees. Help the tree produce a new flush of foliage by watering.
Cedar–apple rust, cedar–hawthorn rust, and cedar–quince rusts are now sporulating on cedars in central Illinois. I have also had reports of galls producing spores in northern Illinois. If you have problems with these rusts on apples, crabapples, and hawthorns, try to locate the alternate host in your area now. If it is on your property, remove new galls next winter before they mature. Mark your calendar now. Sprays for apples, crabapples, and hawthorns should have been applied about 2 weeks ago to protect them from spores released over the past 2 weeks.
White pines have been the number-one host this week. They do not have an infectious problem or something that will easily go away. Affected pines generally lose color in entire branches, or the tree suddenly wilts and dies. Roots are sparse, with rotted cortex tissues. Lab tests have failed to reveal a cause, and the problem has been dubbed white pine decline. This problem will be discussed in an upcoming issue. Meanwhile, fungicides and insecticides cannot help. Concentrate efforts on cultural conditions by providing water during drought, mulching to maintain a more uniform soil temperature, and fertilizing with acidic fertilizer in the fall.