Spraying for apple scab starts as soon as leaves emerge in spring, before any scab symptoms are visible, since the fungus infects new leaf tissue as it opens rather than waiting for an existing infection to show.

What's the Full Spray Schedule Once Treatment Starts?

After the first spray at leaf emergence, Liquid Copper Fungicide Spray is applied again once the leaves are fully developed, and a third time as fruit begins to form. Beyond that initial schedule, treatment continues at 7- to 14-day intervals as needed, with a shorter interval during stretches of frequent rain, since wet conditions let the fungus keep producing new spores.

Does Weather Affect How Urgent It Is to Start Spraying on Time?

Apple scab is most aggressive in springs that stay mild, around 60 to 70 degrees Fahrenheit, and wet, since that combination is what lets the fungus spread fastest once leaves emerge. Starting the spray schedule right at leaf emergence matters more in a mild, wet spring than in a dry one, since delayed treatment gives the fungus a wider window to establish.

Frequently Asked Questions

Is it too late to start spraying if the leaves have already fully emerged?

No. The schedule's second application happens once leaves are fully developed, so starting there still offers protection, though starting right at leaf emergence protects the earliest, most vulnerable new growth as well.

What fungus causes apple scab?

Venturia inaequalis, a fungus that infects apple leaves as they open in spring.

How much does Liquid Copper Fungicide Spray cost?

$18.95 for a 1-pint concentrate.

Does spraying in spring also prevent apple scab from coming back next year?

Not on its own. Spring spraying protects the current season's leaves, but the fungus can still overwinter in fallen leaves and reinfect the tree the next spring unless fallen leaves are also cleared each fall.