Friday, May 31, 2013
May 2, 2012 was largely responsible for helping make the 2012 pecan crop possible during a year of record heat and drought. So this year, we welcome another Spring flood to help fill up the subsoil water reserves we may so desperately need come August.
Thursday, May 30, 2013
When I travel to pecan meetings in the south, I often hear horror stories of massive yellow pecan aphid outbreaks in the early part of the growing season. At high populations, these sap feeding insects can literally drain the life out of pecan leaves.
Fortunately, I have never seen a springtime outbreak of yellow pecan aphids in a northern pecan grove. But this doesn't mean that yellow pecan aphids don't occur in our area. This spring, I've spotted a very light population of yellow aphids feeding on the underside of our pecan leaves (photo at left). In the photo, an adult yellow aphid is feeding on sap flowing through the main mid-rib of a pecan leaflet. Above the adult you can see a small yellow aphid nymph moving across the leaf surface in search of a good feeding spot.
While scouting our trees, I also discovered one of the main deterrents to yellow pecan aphid outbreaks . The convergent lady beetle is one of the most common, native, biological-control agents found in pecan-tree canopies (photo at right). Both adults and their larvae actively seek out and feed on yellow pecan aphids.
|Yellow pecan aphid, Monelliopsis pecanis|
|Convergent lady beetle, Hippodamia convergens|
Wednesday, May 29, 2013
3-flap graft was placed on a side limb of a young sapling. If you look at the top of this tree, the stump visible between the two upper-most shoots was probably the location of a second 3-flap graft that ended up not taking. In any case, the new shoot from the successful graft is only about 8 inches long--way too little growth for a new scion during first year after grafting. The upper portion of this tree should have been pruned off as soon as the shoot on the successful graft was 2-3 inches long (at that point you are certain the graft has succeeded) . All those leaves and shoot growth above the graft only served to slow the growth of the scion.
bark graft to place the scion on the stock. Once the buds on the scion had grown out about 3 inches, I selected the strongest new shoot to become my new central leader and pruned off all the competing scion buds. This photo was taken in mid-July and I had over 3 feet of new growth that could be easily trained to a bamboo stake.
Tuesday, May 28, 2013
Friday, May 24, 2013
With the later than normal arrival of Spring, the grafting season started late this year. however, I looked at the long term forecast and it looks like were are going to have at least another week for grafting pecans.
Tuesday, May 21, 2013
Friday, May 17, 2013
Wednesday, May 15, 2013
|Greenriver pistillate flower development|
Tuesday, May 14, 2013
In the past, we have experienced severe outbreaks of this pest. Larvae became so numerous that trees were defoliated. Although outbreaks of this sawfly are rare, we scout the pecan grove every spring to avoid letting this insect become a problem.
Chewing large holes, or entire leaf blades is another, less-common sawfly. The larvae of Megaxyela major (Cresson) is yellow in color with prominent black spots and a black head capsule. Larvae grow to 3/4 inch long before dropping to the ground and pupating. This sawfly has the curious habit of curling around a leaf's rachis or midrib during daylight hours (photo at right). As night falls, the larvae continue to feed on entire leaves often leaving just the midrib. We have never had a serious outbreak of this sawfly species.
Monday, May 13, 2013
Looking back over previous blog posts, I discovered that I first noticed pistillate flowers as early as April 6th in 2012. That represents a 5 week swing in crop development from 2012 to 2013. In 2012, we were three weeks early. This year we are 2 weeks late. In 2011, we had a more normal spring with female flowers first appearing on April 28th.
Friday, May 10, 2013
Tuesday, May 7, 2013
snow in May. Since that time, spring temperatures have returned and pecan trees have resumed growing new leaves and shoots. Once the new growth expanded a little bit, I noticed a touch of frost bite along the margins of some leaves (photo of Gardner terminal at right). Not every leaflet is affected and the terminals of new shoots look fine.
This marginal leaf burn reminds me of potato leaf hopper damage. However, if you inspect the leaves carefully you won't find the feeding scars on main leaflet veins that are the tell-tale sign of leaf hopper damage. This cold weather leaf burn appears more random, with the severity and location of damage related to the leaf growth stage during the cold snap more than anything else.
Since new shoot terminals were not damaged on any pecan tree I've looked over, pistillate flower production should not be effected by last weekend's cold and snow.
Friday, May 3, 2013
This morning I traveled to Miami County, Kansas for a grafting school and was able to capture a photo (above) of some of the record breaking late snowfall that fell across Eastern Kansas and Western Missouri last night. The snow melted quickly and temperatures never fell below freezing (32 F). Since emerging green tissues on pecan trees can tolerate down to 28 F without injury it looks like the 2013 pecan crop is still OK. However, the record cold spring we have been experiencing has delayed pecan tree growth by nearly 2 weeks.
Thursday, May 2, 2013
In the photo above, look carefully at the shape, size, and texture of the catkins produced by the Kanza and Osage cultivars. At this time during the season, the catkins on the protandrous Osage shoot have already grown plump with the individual pollen sacs clearly visiable. It won't be long until these catkins will begin to shed pollen. In contrast, the catkins on the protogynous Kanza shoot are narrow, not yet fully extended, and the pollen sacs still tightly bound along the catkin's stem. These catkins will release their pollen much later.
As the season progresses, the differences in catkin size and shape become even more striking. Check out the photos from last spring.
Wednesday, May 1, 2013
In the photo at right, two new holes have been drilled to the right of three holes made the previous season by this bird.
Sapsuckers drill holes in the bark starting at pecan bud swell. These birds create the holes in order to feed on the abundant and sugary sap that is flowing up the tree trunk in early spring. You will find that sapsuckers prefer certain pecan cultivars over others. I have never seen a 'Stuart' pecan tree that isn't riddled with sapsucker holes.
Although truck damage can look awful, a well tended pecan tree can withstand sapsucker feeding without significant yield loss.