It’s beginning to look a lot like ... spring!

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The first step in planning for this year’s apple crop is addressing last year’s insect and disease problems, said a University of Illinois Extension green industry specialist.

“Besides early spring pruning to promote good fruiting and branching, attention to dormant oil sprays and the first of many disease and insect prevention cover sprays should be considered,” said Richard Hentschel.

“It is easy to see when an insect has been feeding on the foliage or fruit. What is not so easy to see are overwintering scale insects on the trunk and branches that can keep the fruit tree vigor down or find their way to the young, developing apples.”

Each female scale can produce dozens of young as they hatch from eggs beneath the protective female scale, he noted. These young, called “crawlers,” will move to younger branches and twigs and newly developing fruit before settling down permanently and creating a protective scale.

“Dormant oil sprays are used before any fruit tree growth begins and should be done while the outdoor temperatures remain above freezing for at least 24 hours to be most effective,” he said. “Attention to coverage of the canopy is essential. The dormant oil spray will smother the overwintering scales.

“As a bonus, other fruit tree insects that are overwintering on the trunks will also be managed. If you miss the dormant oil spray, growers will have to rely on their following cover sprays to control the young crawlers.”

Cover sprays get their name from the intent to keep young, developing fruits “covered” to protect them from disease. Since the young fruits need to be protected from insects, too, most cover sprays today contain fungicides for the prevention of a variety of foliar and fruit diseases that can cause problems and an insecticide to prevent insects from laying eggs on or in the fruit. The challenge is to be sure the tree foliage and the developing fruit remain covered through to harvest.

Most cover sprays will need to be started when the fruit tree buds are just beginning to open. This is most often referred to as “green tip,” when the green leaves are just beginning to emerge from the bud scales and all that’s visible are the green tips of young leaves.

“In the beginning of your spray cycle, cover sprays may need to be applied every seven to 10 days,” Hentschel said. “As the season progresses, those cover sprays will need to be repeated every 10 to 14 days.

“Early in the season, while the cool, moist weather is with us, diseases are the big concern. Later, in the warmer, dryer months, insect feeding may be more of a concern.”

Hentschel said if some of those early cover sprays are missed and diseases have developed, later cover sprays will keep the diseases from getting any worse.

“You should use the calendar as a guide and count days between sprays,” he said. “If the weather is rainy, you need to be prepared to re-apply a cover spray as soon as the weather allows and start counting all over again.

“Your local weather temperature patterns along with the fruit trees, spring development will help you determine when the dormant oil spray should be applied and when cover sprays should start. Growers should read and following any labeling instructions carefully, regardless of the product being used.”