Monday, November 4, 2013

Northern pecan cultivars and fall foliage color

    Establishing early-ripening cultivars is critical for successful pecan growing along the northern edge of the pecan tree's native range. Over the past couple of months, I've photographed many cultivars adapted to northern pecan culture as they ripened this fall (25 Sept. 2013, 30 Sept. 2013, 9 Oct. 2013, and  21 Oct. 2013).  However, ripening date is not the only characteristic that is important for assessing the adaptability of a cultivar for northern pecan production.  
    Today, I photographed a Stuart tree growing next to a Greenriver tree. As you can see in the photo above,  the Greenriver tree has developed a nice yellow fall color while the Stuart tree is mostly still green with a touch of fall browning.   Greenriver, like most northern pecan cultivars, starts to shut down earlier in the fall than southern cultivars, such as Stuart.  This earlier entrance into winter dormancy means that Greenriver would be far more prepared to withstand a sudden blast of winter cold than the ill prepared Stuart tree.
Kanza, 4 Nov. 2013
Many of today's early-ripening cultivars represent hybrids of cultivars of northern and southern origins. That is why we see cultivars like Pawnee and Osage still holding on to their summer green foliage all the way into early November. Although early ripening, Pawnee and Osage act like their southern ancestors when it comes entrance into fall dormancy. This might explain why we have seen cold injury on Pawnee and Osage in some years. Kanza is also a hybrid of northern and southern ancestry, but look at our Kanza trees today (photo at right). Its no wonder that we have not seen winter injury on Kanza across KS, MO and IL.