Wednesday, September 17, 2014

Gardner looks promising in the Bootheel

    We established a pecan cultivar trial down in the Bootheel of Missouri several years back and those trees are starting to yield some first impressions. On my last visit to the planting, a pecan cultivar called Gardner caught my attention (photo at right). Besides a nice crop of nuts, Gardner trees appeared to have far less honey dew and sooty mold covering their leaves as compared to the leaves of all other cultivars in the trial. I'm not suggesting that Gardner is resisitant to aphid feeding because I saw definite signs of aphid feeding on the leaves. However, less honeydew on the foliage indicates that fewer aphids were feeding on these Gardner trees.
    In future years, I'll need pay particular attention to how Gardner fares during an outbreak of black-margined aphids.
    Gardner was originally found as a street tree growing in Gardner, KS. The origins of this seedling pecan are not known but I can say with certainty that Gardner is a seedling of an improved pecan cultivar.  The nut is large (photo at left) averaging 7.23g (63 nuts/lb.) and yielding over 57% kernel.
   Gardner is similar to Pawnee in terms of ripening date and the nut even looks a lot like Pawnee. However, Gardner nuts appear more round in cross-section as compared to the more flattened Pawnee. Also like Pawnee, Gardner has a protandrous habit and is susceptible to pecan scab. Fortunately, scab did not appear to be a problem for any of cultivar in our trial this year.

    I cut open a Gardner nut during the first week of September and found the kernel to be well filled (photo at right).  If we can keep the scab under control, Gardner looks promising.

Monday, September 15, 2014

Checking on pecan nut maturity

Mullahy, 15 Sept 2014
    Beginning in early September, I make a trip around the farm each week to check for pecan ripening, hoping to spot yet more pecans with split shucks. This week Mullahy had split about 20% of its shucks (photo at right). I pulled down a couple of nuts and pulled back the husk to check on the nut inside.

    Even though the shuck had split, the Mullahy nut inside had not fully developed its brown shell color and the nut was so wet with moisture, beads of water formed on the shell of the nut (photo at left). This pecan will need a couple of weeks drying time before the kernel would become dry enough to be considered edible.
    It is interesting to watch how pecan cultivars ripen in the fall. When I came to one of our Goosepond trees I found that the shuck had not split but the nut inside was fully colored  and was loose in the shuck (photo at right). I wouldn't be surprised to see the shuck pop open on this cultivar by the end of the week.
    Since I was finding advanced stages of ripening on a couple of early maturing pecan cultivars, I decided to check a couple of others. I cut the shuck off a Peruque nut (photo at left) to find that the nut had begun to separate from the shuck and the shell had developed about one-half its normal shell color. Peruque should split shuck before the end of September.
   Canton usually ripens the same time as Peruque, but the nut I cut open today was still mostly white with only a smattering of the markings that will turn black when the nut is fully mature. Looks like Peruque will ripen well ahead of Canton this year.
    The late spring freeze we experienced last April is going to play havoc with the normal order of ripening this year. Osage broke bud early in the spring and suffered serious freeze damage.  Osage trees re-budded from primary buds located at the base of  last year's shoots but the need to re-leaf  threw the timing for pistillate flower formation back by a couple of weeks. As a result, Osage nut development has been behind schedule all season. When I pulled a Osage nut from the tree and cut into the shuck, I found not even the slightest indication that this cultivar had started shuck dehiscence (photo above left).  Osage will ripen well before frost this fall but it will probably split shuck at least 2 weeks later than normal.  

Friday, September 12, 2014

Remnants of an aphid outbreak

   During last week's tour of pecan orchards in SE Missouri, I found evidence that many trees had suffered from a massive explosion of pecan aphids. By the time I visited the trees, the aphid population had crashed and largely disappeared. However, the aphids left behind some tell-tale signs of their sap-feeding activities.
   Black-margined aphids produce huge amounts of honeydew as they feed. The honeydew quickly covers the leaves with a sugary-sticky film giving the leaves a glossy appearance. Over time, the black sooty mold fungus colonizes the honeydew painting the leaves black (photo at right). The sooty mold fungus grows entirely on the honeydew and does not actually infect the leaves. In fact, you can take your finger nail and scrape the fungus off the surface of the leaves.
   The black pecan aphid is less common in northern pecan groves but I found evidence these aphids had been feeding on SE Missouri pecan trees. As the black aphid feeds on pecan foliage it causes angular yellow and necrotic blotches on the leaves (photo at left). The black aphid tends to feed on leaves on lower and interior leaves. Eventually, black-aphid-damaged leaves drop from the trees causing early tree defoliation.

Wednesday, September 10, 2014

Warren 346 ripens early

Warren 346, 10 Sept. 2014
   I was taking a small tour group on a walk through the Pecan Experiment Field when I was surprised to find some fully ripe pecans on one of our Warren 346 trees (Photo at right). Warren 346 normally splits shuck in early September but with the cooler-than-normal summer we've had, I was expecting pecan ripening to be delayed. However, it looks like things might not be as far behind as I originally thought.
  Warren 346 is an interesting pecan cultivar based strictly on its early ripening date. The original tree was found in a native pecan grove near Wheeling, MO down in the Grand River flood plain. The native trees in this area of Missouri are growing in the extreme northwestern corner of the pecan tree's native range. 
    Warren 346 nuts are small, averaging 4.72g/nut (96 nuts/pound). Pecan kernel is above average for a native pecan, averaging nearly 51% nut meat. The tree has an upright growth habit and is prone to developing branches with narrow crotches.