Wednesday, April 24, 2013

Cold overnight temperatures slow pecan tree development

     I woke up this morning and immediately checked the temperature outside. The morning low was 33 F with a brisk northern wind that made me question if winter was making a come back this week.  Later this morning, I checked the pecan trees for any signs of cold damage. Emerging catkins and shoots were are still healthy and green (photo above).
     Cold overnight temperatures this spring have really slowed pecan leaf burst. At this point, I'm pretty sure our grafting season is going to be significantly later than normal. How late will depend on when we finally start getting warm overnight temperatures.
    There is one advantage to watching this Spring's slow-motion leaf burst. You can definitely see  differences between protandrous and protogynous pecan cultivars (photo at left).  Protandrous cultivars shed pollen early in the pollination season and before their pistillate flowers become receptive. At this time of year, protandrous cultivars seem to be covered in emerging catkins while new shoots are only beginning to emerge. Shepherd is a protandrous cultivar.
    Kanza is a protogynous cultivar. Pistillate flowers on protogynous cultivars develop early in the polination season becoming receptive to pollen well before late developing catkins begin to release pollen. In the photo above, I've pointed out a Kanza catkin that is only now emerging. Most of the active new growth on this Kanza stem is developing vegetative shoots.  Pistillate flowers will develop at the ends of these new shoots.