In central Illinois, cedar-apple rust galls have been sporulating on red cedar since about April 21. Galls of cedar-quince rust were seen sporulating on cedar a few days later. To protect hawthorns from the stem-damaging cedar-quince rust, apply the first protective fungicide sprays when Red Delicious apples in your area are flowering. If you use a fungicide with some systemic activity, you may be able to delay sprays 3 or 4 days.

On May 1, apple scab sporulation was apparent on crabapples on the University of Illinois campus in Urbana. According to weather data, the required wetting criteria (a combination of leaf surface wetting and temperature) for scab infection have been met in central Illinois. This early infection and sporulation probably indicates that we are in for a heavy scab year. The first sprays for scab should be applied at budbreak to target primary infection. If the first sprays are delayed and late fungicide sprays are applied, there may still be some efficacy on the secondary infection. Still, no one can accurately predict efficacy of late sprays.

Fire blight has not yet reared its ugly head in central Illinois. This bacterial disease infects under precise environmental conditions monitored by a forecast system used at the University of Illinois orchards. As of May 1, conditions for infection had not occurred. Fruit pathologist Dr. Steve Ries said that if conditions stay cool through bloom, fire blight is not likely to be a problem in central Illinois.

Sphaeropsis blight on pine has been a major problem in the past several years. The new strain that causes oozing cankers is particularly damaging to pines. If you have diagnosed this problem on your trees in the past and are considering fungicide applications, remember that three applications are necessary. The first application is made at pine budbreak; the second when candles (new growth) are half elongated; and the last when needles are fully expanded. Watch the pines in your area to know when these stages have been reached.