Tuesday, September 30, 2014

Pecan cultivars ripening by September 30th

Faith, 30 Sept. 2014
     The pecan ripening season is moving right along. Today, the last day of September, I found that five more pecan cultivars had split open their shucks since last week (photos at right and below). Gardner, Faith, and Pawnee always seem to ripen at the same time and this year was no exception. However, when checking the nuts for ripening date, I had to make sure to check nuts well above the April 15th freeze line in order to make an accurate assessment.
    Also ripening over the weekend was Surecrop and Posey.  Posey's shuck split is a little difficult to see at first. Look carefully at the photo below and you will note that the shuck has opened up at the very tip of the nut. If you press gently on the shuck you would find that the shuck has actually split down each suture all the way to the base of the nut. In a week or so, shucks will start to dry and shrink from moisture loss. At that point, the shuck will start to curl back away from the nut and Posey will actually look  like a fully ripe pecan.   

Gardner, 30 Sept. 2014
Pawnee, 30 Sept. 2014
Posey, 30 Sept. 2014
Surecrop, 30 Sept. 2014

Friday, September 26, 2014

Pecan Cultivars ripening by September 26th

Colby, 26 Sept. 2014

    Our beautiful, early-fall weather continued this week and more pecan cultivars have split open their shucks. Today I found that Colby, Grotjan, Henning, Peruque, and Witte had ripened since the last time I checked (photos at right and below).
    Henning is usually one of our first pecan cultivars to shuck split, but this year it ripened about two weeks later that normal. This delay in ripening was caused by the April 15th killing freeze. At the time of the freeze, Henning had broken bud and even started to push out some leaves. All exposed green tissue was killed and the tree had to start growth again from secondary buds. The regrowth did produce a few pistillate blooms but the whole flowering, pollination, and nut development process occurred two weeks later than normal. So it is not surprising that Henning's shuck split ended up two weeks late this year.
Grotjan, 26 Sept. 2014

Henning, 26 Sept. 2014

Peruque, 26 Sept. 2014
Witte, 26 Sept. 2014

Monday, September 22, 2014

Cultivars ripening by September 22

Osage, 22 Sept. 2014
   On such a beautiful day, I decided to look over the orchard in search for any more cultivars that have split shuck. I found three: Osage, USDA 64-11-17, and USDA 61-1-X.  These three cultivars all originated from the USDA pecan breeding project. Osage resulted from a cross of Major and Evers. USDA 64-11-17 have Barton and Starking Hardy Giant parents, while USDA 61-1-X came from a cross of Chickasaw and Starking Hardy Giant. Photos of these cultivars are posted at right and below.
USDA 64-11-17, 22 Sept. 2014
USDA 61-1-X, 22 Sept. 2014

Thursday, September 18, 2014

Cultivars ripening by September 18th

Canton, 18 Sept. 2014
    After a morning shower, the sun popped out this afternoon and I took the opportunity to check on nut ripening. Three cultivars have split shuck since I last looked earlier in the week. Canton, Norton, and Goosepond are now ripe as shown in the photos.
Norton, 18 Sept. 2014
Goosepond, 18 Sept. 2014

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.

Friday, September 5, 2014

Water makes pecan kernels fill

   After an extended period of dry and hot weather in August, we received 5 inches of rain at the Pecan Experiment Field on September 1st. Up until that big rain storm, the dry weather had inhibited kernel fill and it was looking like kernel quality would ultimately suffer. I was curious to see how our pecans would react to the sudden resupply of soil moisture, so I decided to collect some nut samples.

   On the day following the rain (Sept. 2) and for the next two days, I harvested some Kanza nuts from trees growing at the research station. I then stored the nuts in the refrigerator until all samples were collected, then cut open nuts just before taking the photo above.
   From the three nut samples pictured above, we can learn a lot about how pecans fill kernel and which portions of the kernels are most affected by drought stress. In a previous post, I described how pecan kernel forms inside the nut--kernel tissue is first deposited just inside the seed coat then grows inward to eventually fill the inside of the shell. However, close inspection of the nut collected on Sept. 2 you will note recently formed translucent kernel material on each kernel half closest to the inner wall partition (red arrows). The rain had already stimulated new kernel deposition in an area that had suffered from drought stress. If the weather had remained dry, the under side of each kernel half would have remained undeveloped and the kernels at harvest would have appeared to have a "hollow back" side.
   Two days after the rain, solid kernel had developed all the way around the inside of each kernel half. By Sept. 4, the kernel inside the Kanza nut had expanded to the point of almost eliminating all air spaces inside the shell. It is truly amazing how quickly a pecan can fill its kernel when given a plentiful supply of water. It will be interesting to see how Kanza turns out this year in terms of percent kernel. 

Wednesday, September 3, 2014

Pecan weevils emerge

    After a hot and very dry month of August, a large storm spread over our area on the 1st day of September. Along with an amazing lightning display and high winds, this storm dumped 5 inches of rain on our pecan grove. The much needed moisture will help fill out pecan kernels but has also created the prefect soil conditions for pecan weevil emergence. Today we collected up to 5 weevils in a Circle trap.
    When weevils emerge from the soil they crawl and fly up into the nearest pecan tree. Once in the tree's canopy, both male and female weevils search out a nut cluster (photo above). After arriving at the nut cluster, male and female weevils will find each other and mate. Several days after mating, the female weevil will begin laying eggs inside the nut.

    It is fairly easy to tell the difference between male and female weevils. Female weevils have a much longer proboscis than their male counterparts. In the photo at left, the male weevil is the insect on the upper right. The female is located on the lower left side of the photo. Looks like these two will be doing the weevil tango before too long.
   To remind everyone that weevils can and do fly, I was also able to photograph a weevil adult preparing to take flight (photo at right). A weevil will raise its two hard wing-covers to reveal a pair of translucent, copper-colored wings. A pecan weevil may not be the best aerial acrobat, but this insect will fly from un-managed, weevil-infested, native trees into your orchard just to find a place to lay eggs. That it one reason why we have been setting up traps outside of our orchard. I don't like to be caught unaware by migrating weevils.
    We will be spraying for weevil starting Thursday Sept. 4.