Apple management: Bloom for most

By Terence Bradshaw

There are several key points to consider in managing apple crops this week: the lack of rain, and bloom. The dry weather has reduced scab infection pressure, but has also put developing ascospores into a brief ‘hibernation’ period. Trust that the next significant wetting period will release a large proportion of the season’s ascospores, and remember that many orchards had a fair amount of scab last year. So, during this dry spell, don’t worry too much, but be sure to be fully covered with a fungicide prior to the next significant rain. That might be Tuesday in southern Vermont, or as late as Friday in northern. During bloom, know that captan has been shown to negatively affect pollen germination, and DMI fungicides (FRAC code 3) like Rally, Inspire Super, etc. may negatively impact pollinators, so avoid those if possible.

Once orchards are in bloom, the only insects you should be thinking about managing are pollinators. Where orchards are still in the prebloom / pink bud stage, tarnished plant bug and European apple sawfly are the primary pests to manage, but should only be treated based on trap counts and an assessment of your damage threshold. Most orchards that aren’t shipping fruit to wholesale don’t need to manage those pests, and those that do usually know who you are.

The greater concern as we go into bloom is fire blight. That disease wasn’t especially prevalent in Vermont last year, so neighborhood inoculum is relatively low, but this warming trend going into bloom can rapidly advance bacterial populations where they do exist. Keep an eye on the NEWA fire blight model for you orchard or one near you and be ready with streptomycin if infection conditions are shown and you have open blossoms.

Finally, with rapidly developing leaf tissue and the activity around bloom, this is an important time to keep water and nutrients supplied to the trees. Irrigation should be run if available, and consider ground or foliar-applied fertilizers as needed based on your soil or foliar analyses.

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