Wednesday, July 24, 2013

A late scab spray

Scab lesions on Giles nuts (24 July 2013)

    We made a fungicide application to our scab-susceptible cultivars today. Two things prompted this fungicide application. First, the 5.5 inches of rain that fell on our grove over the past 5 days combined with seasonably warm temperatures have created the perfect conditions for the spread of pecan scab. Secondly, nut development is much delayed this year and our crop is only now entering the period of rapid fruit expansion; a time when pecans are very susceptible to scab infection (photo above).
    So we mixed some Stratego fungicide in our spray tank and went to work. We did not add an insecticide to the spray tank at this time because it is too early for weevils and we haven't seen any sign of fall webworm or walnut caterpillar this summer.  We'll spray for insects in August when stink bugs and pecan weevil start to invade the orchard.
    This morning I photographed a few of the more scab susceptible cultivars that we have in our collection.  Those photos appear below. Each nut cluster was photographed from the same distance which allows for a direct comparison of the stage of nut expansion (nut size) at this date.  Today, the early-ripening Mullahy cultivar is much larger (further advanced in development) than the late-ripening Dooley cultivar but by harvest, these nuts will be roughly the same size.

Hirschi, 24 July 2013

Dooley, 24 July 2013

Mullahy, 24 July 2013