' Jenkins' Pecan 

Additional index words.  Carya illinoinensis, Cladosporium caryigenum, cultivar, variety, disease resistance

'Jenkins' is a new pecan [Carya illinoinensis, (Wangenh.) K. Koch] cultivar released cooperatively by Auburn
University and the Mississippi State University.  'Jenkins' is being released because of its pest-resistance, especially to pecan scab [Cladosporium caryigenum (Ell. Et Lang.) Gottwald], and because it produces high quality pecans, even with minimal care.  We believe  'Jenkins' is suitable both for low input planting and for trial in commercial plantings in the southeastern U. S. 

Origin

'Jenkins' grew from a seed planted near Rena Lara, Mississippi, on the property of Travis Jenkins, for whom the cultivar is named. The seed was planted about 1979.  The seed was open-pollinated, and neither the female nor male parent is known, although ‘Moreland’, 'Owens', and 'Elliott' are thought to be among the seed planted at the location at that time. The health, vigor, foliage condition, absence of scab, and high nut quality of the clone were observed and noted by Jenkins. He collected graftwood from the parent tree in the winter of 1985-86, and sent it to Bill Goff of Auburn University to be included in pecan selection evaluations. In spring of 1986, the first tree ever propagated of the selection was grafted by Goff onto seedling trees on the property of Gus Tompkins near Fitzpatrick, Alabama, as a part of an experiment evaluating 80 pecan selections. In winter of 1987-88, Goff collected wood from these trees and sent it to Richard Mullenax and Freddie Rasberry for grafting in a low-input pecan cultivar trial at the Truck Crops Experiment Station near Crystal Springs, Mississippi. At the same time, scion wood of the selection was also collected directly from Travis Jenkins for the Crystal Springs  test. At the Crystal Springs location, the clone was initially referred to as "Alabama Jenkins", as wood was sent from Alabama even though the parent tree was from Mississippi. The clone has been called Jenkins, Jenkins 1, Jenkins 3, and Alabama Jenkins in various experimental evaluations, but we will hereafter list it as 'Jenkins'.

 Description

Data on performance of  'Jenkins' are available from four replicated experiments - two near Tallassee, Alabama; one at Crystal Springs, Mississippi; and one near Lowndesboro, Alabama.  In addition, observations have been made at numerous grower locations to expand the exposure of the clone to multiple strains of the scab fungus. 'Jenkins' has exhibited low incidence of scab disease (Table 1, Fig. 2).  While our experience suggests that many clones exhibit low incidence initially at sites where they haven't been grown before, Jenkins has not shown a trend of increasing scab, nor have their been instances at any location where the disease has been severe.  This distinguishes Jenkins from many other clones, like Sumner, Pointe Coupee #2, Melrose, and Houma, all of which have exhibited severe scab in certain years or locations in our research. We are hopeful that this absence of severe scab, despite 13 years at one location (Crystal Springs, Mississippi) and despite observations at many humid locations, is an indicator of durable resistance to this disease in this cultivar.

In addition to the scab resistance of Jenkins, the cultivar has exhibited excellent foliage retention and excellent foliage condition in late season in situations of severe incidence of foliage pests resulting in premature defoliation and in poor foliage condition on many cultivars (Table 2).  These excellent foliage condition ratings suggest that 'Jenkins' tolerates common foliage pests likely to have been present at the locations where Jenkins was observed.  In 1999, incidence of pecan stem phylloxera was severe in south-central Mississippi, but 'Jenkins' had light infestation at Crystal Springs. 

Nut quality of 'Jenkins' is very good (Table 3), especially in relation to other clones with outstanding scab resistance.  Kernel percentage is about 54%, with most kernels grading No. 1. Nut size is medium, 28 nuts per kilogram in 1997 at Crystal Springs.  The nut shells easily into halves, and kernel color is bright. In 1999, we sent samples of Jenkins to Nick Sachs and to Bobby Drinkard, both commercial pecan buyers for evaluation, and received favorable reports on market acceptance, along with recommendations that we proceed with release.  Yield estimates from visual observation were made at the Crystal Springs location in 1997 and 1998 (Table 4), and and actua yields were obtained in 1999 from the Jenkins trees only. In 1997 the estimate was 7.7 kg per tree, then 0.5 kg per tree in 1998, and 7.1 kg/tree in 1999. While these yields suggest an alternate bearing pattern, all cultivars in the experiment exhibited a similar trend, including cultivars like 'Owens' with a history of consistent production from grower experience in the area (Travis Jenkins, personal communication), and an alternate bearing index of only 0.22, among the best at Tifton, Georgia (Patrick Conner, personal communication).  A well-managed commercial orchard nearby exhibited the same trend on all cultivars, which included Desirable, Stuart, Forkert, and Jackson (Randolph Smith, personal communication). While long-term yield data is lacking on Jenkins, we are encouraged that the cultivar produced good quality in two heavy crop years, 1997 and 1999.

'Jenkins' exhibits incomplete dichogamy.  Pollen shed on young trees in central Alabama in 1999 occurred from 3 May to 11 May; while stigma receptivity occurred on the same dates, thus the dates suggest neither protandrous nor protogynous flowering habit. Mean catkin length was 7.8 cm, suggesting that the cultivar is protandrous (Sparks, 1992).  'Jenkins' could be interplanted with 'Syrup Mill' and 'McMillan’ as pollenizers (Fig.1). Harvest date (50% of shucks split) occurred in Crystal Springs, Mississippi, in 1997 on 14 October.  This suggests early to midseason harvest, about  3 days before Stuart. 

Availability

Budwood and graftwood is limited and will be supplied to nurserymen only.  All requests should be sent to  W. D. Goff. We have no trees for distribution. 

Literature Cited
Goff, William D., M. Nesbitt, R. Mullenax, F. Rasberry, and B. Graves. 1998. Pest resistant cultivars as a way to reduce input costs. Pecan Industry: Current Situation and Future Challenges, Third National Pecan Workshop Proceedings. 79-89. 
Sparks, D. 1992. Pecan Cultivars, The Orchard’s Foundation. 1^st ed. Pecan Production Innovations, Watkinsville, Ga.

Fig. 2. Occurrence of stem scab lesions on 'Jenkins', 'Elliott' (scab-resistant check), and 'Desirable' (scab-susceptible check) for four years at various locations. Letters in chart represent locations.  Ratings were made in October of each year by counting stem scab lesions on the worst 30.5 cm of shoot growth on the tree. Location codes are as follows: a) the E. V. Smith Research Center near Tallassee in east central Alabama; b)Lowndesboro, Alabama; c) another field near Tallassee, Alabama, to about three miles from site a; d) Crystal Springs, Mississippi; e) Albany, Georgia; f) Auburn, Alabama; g) Columbia, Alabama; h) Walnut Hill, Florida; I) Andalusia,  Alabama; j) Dothan, Alabama; and k) Fairhope, Alabama. A lowercase letter represents one tree. On uppercase letter represents 10 trees.  The hatched lines represent the means of 'Desirable' (scab-susceptible check) and 'Elliott' (scab-resistant check) at all locations and years.