by Bill Goff
While two consecutive rainy seasons with much higher than normal incidence of scab have made it difficult for growers, the increased scab has provided an opportunity for better evaluation of pecan selections for resistance to this devastating disease. Our expansion of cultivar evaluations beyond multiple locations in Alabama into the center of the major commercial pecan production area around Albany, Georgia, has provided further insight. We now have information on how cultivars respond to standard commercial pecan production practices, and how they perform in the presence of heavy pressure from not only scab, but also from the pecan leaf scorch mite, black pecan aphid, and yellow pecan aphid, which are all difficult problems in this area, perhaps more so than in any other area where pecans are grown. With this additional information in hand, we have made several revisions to our recommendation list and some reclassifications of scab resistance levels for cultivars now that we have seen the heavy pressure from scab. Following is our revised pecan cultivar recommendations list for 2014-2015. In addition to pest resistance, another major focus has been early harvest date. The much higher prices in September and October, especially for giftpack quality nuts, has made and will make it essential for growers to have early maturing cultivars to remain competitive. This advantage for early harvest will intensify in seasons prior to an early Chinese New Year, and also in seasons like this one where the harvest is very late due to environmental conditions following the cool spring.
An important development emerged in marketing the 2012 crop. There was a glut of pieces, a shortage of halves, and a shortage of large nuts in general. Chinese demand, and therefore price, was heavily weighted toward large nuts, especially Desirable. The differential preference for Desirable compared to smaller nuts, even high-quality smaller nuts like Schley, was unusual, but needs to be taken into account. Because the western crop is heavily weighted toward Western Schley, a small nut, a continued shortage of large nuts appears to be something you can count on for a while. So, we have adjusted our recommendations and added some large nuts, like Ellis, to address this demand.
We list cultivars we recommend by current observations of scab resistance category (Table 1). Additional characteristics of recommended cultivars are listed in Table 2.
Regarding scab resistance level, I need to stress the word current, as strains of the scab fungus may develop on a selection which makes it worse than currently observed. I further need to stress that the development of strains down the road that attack currently scab resistant cultivars does not mean that planting scab resistant cultivars has no usefulness. Rather, it is in fact, in human regions, paramount to success. With some cultivars, like Elliott, scab incidence has been minor for decades. With Stuart, scab was very light for decades, then became moderate for more decades. Today, over 100 years since Stuart was introduced, it remains only middle of the pack or better in scab incidence. Similar cultivars to Elliott and Stuart certainly exist, we just need to subject the test selections to heavy enough scab pressure initially from multiple strains in many locations to identify which ones they are. Do not let pathologists or others convince you that scab resistance is not useful simply because scab resistant varieties ultimately become susceptible as new strains develop. The resistance, if the proper stringent screening is done in the beginning – and the selection passes it – can last for decades and often for your lifetime. Most selections that “lost” their resistance after a short time never had it to begin with. They were thought to have had it, because they weren’t stringently screened over multiple locations with many strains of the fungus without fungicides under heavy scab pressure. Such stringent screening would have revealed they were really never very resistant to begin with.
Scab Resistance Categories
I will group the cultivars into four categories of scab resistance, based on observations in our experiments as well as observations from other researchers. For established cultivars, the most useful and extensive observations are from grower’s orchards, mainly in Georgia, Alabama, and Louisiana, and these observations are included in the rankings as well.
The categories are excellent, good, mediocre, and poor. A cultivar with excellent resistance has exhibited no scab or minor occurrence even in the total absence of sprays in wet seasons. Good resistance means that we have observed damaging scab in the total absence of sprays in wet seasons, but the disease is usually minor in dry years, or in wet years with a modest spray program of 2-4 sprays. Mediocre resistance means that we will see serious losses in wet seasons in the absence of sprays, but the disease causes little risk with a normal 8-10 spray fungicide program. Poor resistance implies total crop loss almost every season under Southeastern conditions if no sprays are applied, and considerable risk of loss in wet years even when a normal spray program is followed. A grower accepting a poor risk cultivar, like Desirable or Pawnee, should realize that over a season there are many times during prolonged wet spells when sprays cannot be applied, even though the grower is willing to spend the money to do so. This makes the orchard at great risk of crop loss despite best intentions. Also, multiple research evaluations have demonstrated that with current technology growers cannot provide adequate spray coverage in the tops of tall trees, so susceptible cultivars are further vulnerable to significant loss in the tops of trees, a problem avoided with resistant cultivars.
Bear in mind that these categories apply to conditions in humid areas with 45-60+ inches of annual rainfall, and scab would be expected to be less in drier areas. Be aware also that at a given location a new cultivar may be introduced and scab less than categorized for some time until strains develop to attack it, as they have done in our valuations elsewhere thus demonstrating genetic vulnerability.
Cultivars are grouped intofour categories according to how we recommend them. Recommended cultivars are those we feel represent the best overall within their scab resistance category. Cultivars recommended conditionally or for trial are good choices also, but either have less supporting data or have problems identified with them that need to be considered before they are planted. The conditions for conditionally recommended cultivars are specified in the cultivar descriptions below. Cultivars recommended for low input planting are those for growers who will spray, but choose to spray minimally, like organic growers. Last we have added a group recommended for home plantings. Assumptions for cultivars in this group are that they will never be sprayed, so emphasis is on tree appearance and leaf condition, and exceptional pest tolerance, with less emphasis on nut size and tree productivity.
We recommend 7 cultivars that have exhibited excellent scab resistance. Many have nuts too small for commercial plantings, but the smaller nuts often are tastier and more likely to develop high quality kernels in the absence of spraying, so they are good choices for homeowners. Those recommended for home plantings also have exceptionally healthy and pretty foliage, even in the absence of sprays, indicating tolerance to foliage pests as well as to scab.
(USDA Mahan x Major) Type II. 56 nuts/lb. 58% kernel. We now have six years of observations on this selection, and four years of data on fruiting, as we topworked some large trees which had some fruit two years later on this precocious cultivar. While six years is not a long time, bear in mind that the cross was made in 1964, 50 years ago, and some evaluators, like Bill Reid in Kansas, have been evaluating it critically for almost 30 years, and find it suitable. Of foremost importance in the Southeast is scab resistance, and Lakota is outstanding, as good as any we have ever evaluated, in resistance to the disease. After looking at thousands of trees in Georgia and Alabama, many in unsprayed situations in heavy scab pressure, I still cannot find any scab on Lakota. Similarly other observers in other states also report excellent scab resistance for decades, perhaps due to the Major parent. In addition to this, Lakota has exceptional quality, with usually bright kernels, better than Pawnee, again according to Bill Reid. Lakota is quite precocious, and has more nuts on young trees than all cultivars in our test except Creek so far. As with other precocious and highly productive cultivars, overbearing and alternate bearing can become a problem on older trees, but with Lakota this according to Bill Reid, can be managed with proper crop thinning. Hedging also is a tool now available to manage excessive crop. Another drawback is that Lakota produces only a medium-sized nut, about 56 nuts per pound in our early evaluations , with considerable variation in size of nuts even on the same tree. Cluster size is large, 4 nuts per cluster on average reported from the USDA release, but there are some clusters with 7 nuts in our tests. The tree is very strong and vigorous, and needs to be spaced wider than the average cultivar. This is a cultivar that deserves to be planted by those seeking excellent scab resistance, high productivity, early harvest, and high-quality, and are willing to crop thin or hedge, and accept the medium nut size. Lakota is pollinated by Pawnee, Eclipse, Amling, Creek, and Caddo.
GA seedling (Pierce County) suspected to be Pierce x Success. Type II. 45 nuts/lb. 49% kernel. Excel has a unique combination of large nut size, excellent scab resistance, and early harvest date, about October 7. Kernels are bright, but kernel percentage is only moderate as shells are thick. Yields are high, but alternate bearing and overbearing may be a problem on older trees. Excel is recommended for commercial and low input planting, for growers with shakers or access to hedging machines to reduce the excessive crop load. In 2013, I observed enough scab to consider lowering Excel into the “Good” resistance category rather than “Excellent”, but the scab was only in one location and did not recur in 2014, so for the time being, I still consider scab resistance excellent on Excel. Excel is pollinated by Creek, Desirable, Gafford, Caddo, and Cape Fear.
(Major x Shoshoni) Type II. 65 nuts/lb. 52% kernel. A cultivar with excellent scab resistance that we recommend, especially for North Alabama, is Kanza. Kanza is a Major x Shoshoni cross released by USDA in 1996. It has excellent scab resistance and unlike Elliott excellent cold hardiness. Similar to Elliott, it alternately bears but maintains good quality in on years. In our tests at the EV Smith Research Center, kernel brightness has been worse than Elliott, and percent kernel, at only about 49% for Kanza, is also less than Elliott or Headquarters. Perhaps shuckworm damage, which occurs earlier on Kanza than most cultivars, contributed to the lower kernel grades for Kanza in this test. Kanza is suggested for trial plantings in northern areas of the Southeastern pecan belt, where Elliott is too freeze susceptible. It is also recommended throughout the Southeast for those wanting a highly scab resistant cultivar with a very early harvest date in mid-to-late September.
AL seedling (Butler County)Type I. 56 nuts/lb. 50% kernel. Produces a moderate quality nut with bright kernels with occasional speckling. Nuts are medium-sized, and harvest is midseason. It has excellent resistance to scab and foliage pests. It is one of the most pest-free selections we have ever evaluated. Yields have been good to excessive. To maintain quality and reduce alternate bearing, crop thinning will be required.
AL seedling (Macon County), Elliott x ? Type II. 60 nuts/lb. 54% kernel. This tree is likely an Elliott seedling, but nuts are larger than Elliott and have similar quality. Headquarters, tested as HQ2-4, has produced good yields of nuts of good quality with minimal care and no sprays. Scab resistance is excellent, and harvest date is midseason, about October 17. Nuts have a rounder shape than Elliott.
(TX seedling). Type II. 60 nuts/lb. 53% kernel. This selection is recommended for yard tree use only, for which it is an excellent choice. Amling is among the prettiest trees for home use, with good tree vigor, and excellent foliage condition and appearance. If you want a beautiful pecan tree for landscape and home plantings, this is the best choice we can offer. This selection has inconsistent and low yields on young trees and would not be profitable enough in commercial orchards. The absence of overbearing ensures quality and reduces stress on yard trees, which cannot be mechanically crop thinned. Scab resistance is excellent, and foliage has been rated excellent in late season with no sprays. Nut quality is very good.
GA seedling (Mitchell County). 81 nuts/lb. 53% kernel. Like Amling, we recommend this selection for yard tree use, and it is outstanding for that purpose. It has the distinction of being the only cultivar that we have evaluated for many years that has never had a single scab lesion. In other words, we feel like it is the most scab resistant pecan variety that has ever been tested. Nut quality is good, but nut size is probably too small for commercial use. Foliage condition is excellent in late season even with no sprays. For making pecan pies from a yard tree, few if any selections are better.
LA native (Pointe Coupee Parish). 86 nuts/lb. 52% kernel. We collected numerous Louisiana natives from Pointe Coupee Parish, and have evaluated them for many years. Miss L stands out because of pest resistance, good yields, and excellent quality good tasting nuts. We recommend this selection for yard tree use only, as nuts are too small to bring competitive prices needed for commercial plantings. For a yard tree, appearance is beautiful, production is dependable, and taste and quality will be superior to most others in the absence of sprays. Foliage condition is excellent in late season even with no sprays.
Texas native (Lavaca County). 84 nuts/lb. 54% kernel. This selection produces excellent quality, but small nuts, with little care. Quality is attested by the fact that this cultivar was the “State Champion Native” at the Texas Pecan Show in 1991. It has performed well in our unsprayed test at Fairhope. It would be a good choice for home plantings, and perhaps low input or organic plantings if the high quality excellent tasting nuts offset the small nut size. It is reported to scab some now in Texas where it has been more widely planted.
Next, we’ll discuss cultivars with good scab resistance, which can be grown with a minimal fungicide spray program.
GA seedling (Dooly County). Type II. 44 nuts/lb. 57% kernel.This is an exciting new cultivar that will be patented by Elliott Ellis, who has 30 years of observation on its performance. This selection combines several highly desirable traits, and has no major flaws, other than it has not been evaluated in replicated trials yet long enough. Scab resistance is good, similar to Sumner. It has exhibited an ability to produce excellent quality, even when nuts are large and crop is heavy. Harvest date is early to mid-season, a few days earlier than Desirable. The Chinese demand for large nuts should make this a valuable nut for the export market, and it would be highly valued here for the giftpack and inshell market as well. It is moderately susceptible to black aphids, and needs close monitoring for that pest. Ellis is pollinated by Oconee, Desirable, Amling, Apalachee, Caddo, Creek, and Cape Fear.
USDA (Mohawk x Starking Hardy Giant). Type I. 65 nuts/lb. 55% kernel.This cultivar has a confusing history. Andy Clough discovered a tree in Pierce County, Georgia, that he thought was a seedling. Because of its promising characteristics he applied for and was granted a patent for the selection, which he named Eclipse. Later other trees with similar characteristics surfaced, and these trees were thought to be USDA selection 1963-16-182, a Mohawk x Starking Hardy Giant cross, a full sib of Pawnee. Molecular profile evaluations by USDA comparing Auburn University grafted test trees grafted from wood taken from the parent Eclipse tree with USDA 1963-16-182 established that the two were the same. In Kansas, Bill Reid reports poor yields http://northernpecans.blogspot.com/2013/03/what-about-usda-63-16-182.html, but attributes that partly to severe ice storm damage, not a concern in most of the Southeast. Currently USDA scientists are considering releasing the cultivar for use by growers, but not naming it, as they feel there is insufficient research data to support the naming. For the time being, I will refer to this selection as Eclipse, since there is a legal patent by that name. Eclipse has extremely early harvest date, about September 5, two weeks or so earlier than Pawnee. The nuts are smaller than Pawnee and are longer and more slender. There are about 65 nuts per pound, with 55% kernel. Kernels are also similar to Pawnee, with bright kernel color and occasional flecking. Yield potential from grower observations appears to be greater than Pawnee, with less alternate bearing. Because of overproduction, it will likely need crop thinning or hedging, as Pawnee does. Scab resistance, at least currently, is much better than Pawnee and similar or better at this time than Sumner. The primary disadvantage will be the small nut size, but the selection offsets that disadvantage with the advantage of the very early market window. We suggest this cultivar for those hoping to get an early jump on harvest and a very early-season market advantage.
AL seedling (Baldwin County). Type II. 56 nuts/lb. 51% kernel.This cultivar has been highly productive and consistent. Scab resistance has been good on this cultivar, similar to Sumner. In wet years with no sprays scab losses can occur, but scab is easily controlled with a modest fungicide program of 3-4 sprays. Kernels are somewhat dark and occasionally, like Pawnee, have ugly dark kernel markings. Harvest date is about October 20. This selection may be useful for those seeking high yields with minimal input.
GA seedling, (Tift County) Type II. 50 nuts/lb. 50% kernel. Sumner is a productive cultivar with good kernel quality, high and consistent yields, large nuts, and good scab resistance. A major disadvantage for Sumner, like Oconee and Gloria Grande, is that it is highly susceptible to black aphids, and damage from these pests can be serious unless systemic insecticides or aggressive scouting and spraying are used. Sumner also has the disadvantage of late harvest, about 11 days after Stuart. We have frequently seen total crop loss to scab when no fungicides are used on this selection, although the disease is easily controlled with a modest spray program of 3 or 4 fungicides. Sumner may have a niche in the Chinese market, as demand exists there for large, long nuts. With the late harvest, Sumner will be difficult to ship in time for the Chinese New Year.
FL seedling, (Santa Rosa County). Type II. 72 nuts/lb. 51% kernel. Elliott is an older cultivar widely planted in the Southeast. It has been the standard for scab resistance and retains good resistance in most locations over 80 years since its release about 1925. The reason for its conditional status is because Elliott has known flaws that need to be considered. The widespread planting has allowed strains of the fungus to develop at certain locations such that the usual excellent scab resistance has weakened, resulting in our current scab resistance rating of good. In the face of these strains of the fungus, scab resistance is no longer strong enough to grow Elliott without sprays in many locations. Foliage condition on Elliott on unsprayed trees is often weak, as Elliott is susceptible now to foliage diseases and is quite susceptible to yellow aphids and sooty mold accumulation. Elliott trees in our unsprayed test are usually ugly and black in late-season and defoliate early in the absence of sprays. Alternate bearing is severe, though Elliott usually maintains high quality with excellent bright kernels even in heavy on-years. Elliott’s early budbreak makes it quite susceptible to spring freezes. Elliott has low yields on young trees when compared to similar selections like Baby B and Headquarters.
(GA seedling (Dougherty County) Type II. 67 nuts/lb. 50% kernel. This tree, tested as Pippin 99-4 is exceptional with respect to foliage appearance and condition. The large leaves remain on the tree in full canopy even in years with heavy pressure from diseases and insects. Likely related, yields are heavy and consistent. Nuts resemble Elliott, but harvest date is very early, similar to Pawnee and Kanza. Scab resistance is good, but some spraying will be required. Nut quality is not as good as Elliott, but yields are far higher and Baby B is very early, similar to Pawnee and Kanza.
Among the many cultivars in this category, we recommend five: Caddo, Creek, Zinner, Apalachee, and Kiowa.
USDA (Brooks x Alley). Type I. 70 nuts/lb. 54% kernel. The small, football shaped nut of this cultivar is consistently well filled with bright kernels. The nut has good cracking qualities, and is suited to shelling markets. It is a very prolific and consistent bearer. Scab is easily controlled with sprays, but it is black pecan aphids. Harvest is early, about October 9.
(Mohawk x Western?) Type I. 54 nuts/lb. 50% kernel. Variety trial results understate the yield potential of Creek, as the small compact trees tolerate crowding and should be spaced closely, resulting in high per acre yields. It is only conditionally recommended, as trees must be crop thinned or hedged, have good irrigation, aphid control and late fertilizer applications or quality and alternate bearing are intolerable. Scab is easily controlled with sprays, and this cultivar has relatively low levels of aphids and sooty mold. When managed aggressively, Creek is a very dependable producer of high yields of good quality nuts which can be sold on the early market. In terms of net dollars per acre, this one is hard to beat, and much less risky than cultivars that have scab and aphid problems. Creek is pollinated by Oconee, Caddo, and Pawnee.
(AL seedling (Baldwin County) Type II. 56% kernel, 48 nuts per pound. This cultivar was selected for evaluation by Bill Goff about 1990, after a recommendation from Baldwin County pecan grower Stanley Zinner. We planted trees in 1990 into a test planting at the E. V. Smith Research Center in central Alabama. Yields were mediocre, but quality was excellent and consistent. Kernels are very bright, among the most attractive of any we have tested. We feel the poor yields have to do with black aphid damage, as the selection is highly susceptible to this pest. Similarly, Oconee performed poorly in this test for the same reason. If black aphids can be monitored carefully and aggressively controlled, this cultivar may have a place for those seeking a fairly large nut of high quality and beautiful color that might not need crop thinning. Zinner is pollinated by Caddo, Cape Fear, Apalachee, Creek, Desirable, and Gafford.
USDA (Moore x Schley). Type I. 80 nuts/lb. 57% kernel. One of the most thoroughly-evaluated cultivars before release, tested as USDA 48-13-311, Apalachee is planted in grower trials and research orchards in Georgia, Alabama, Texas, and Louisiana. Consistently for many years, it has exhibited remarkable yields of high quality nuts with early harvest date. The high quality, beautiful kernel appearance, and early maturity of the nuts have resulted in good prices for the limited quantities available despite the very small nut size. Kernel percentage is about 57-58%, with 80 nuts/lb. In addition to small nut size, problems include alternate bearing and black aphid susceptibility. Kernels can be dark, especially if left to lay on wet ground. Bird predation is a serious problem, so nuts must be promptly harvested.
(Mahan x Desirable) Type II. 45 nuts/lb. 53% kernel. This cultivar, released 38 years ago, is enjoying a renaissance, as demand for large pecans has increased because of the Chinese preference for large size. Before the Chinese market, Kiowa was in less demand, as kernels are somewhat darker than Desirable, and shellers liked it less. The roasting process in China darkens kernels anyway, and the kernel color is less important. The overbearing characteristic, and resulting limb breakage, poor quality, and alternate bearing were alleviated to some degree by crop thinning, even though it is difficult to shake out nuts on this selection. Hedging offers another tool by which excessive cropping can be dealt with. Since Desirable scab has become much worse than Kiowa, in most locations, Kiowa can be substituted, and sells readily for equal price. Kiowa has better scab resistance than Desirable, but is more susceptible to black aphids. Harvest date for Kiowa is a few days later than Desirable.
Since scab is such a major limiting factor in pecan production in the Southeast, we do not fully recommend any cultivars with poor scab resistance. However, some cultivars are so exceptional regarding other characteristics, that they are worthwhile to plant despite enormous scab risk.
(Success x Jewett) Type I. 46 nuts/lb. 53% kernel. This old standard cultivar we conditionally recommend. The conditions involve scab control. Desirable should not be planted in low wet areas with poor air flow. Desirable orchards need to be open, with no more than 50% canopy coverage. Growers need to be prepared to spray fungicides at 7-day intervals during wet periods. Advantages of Desirable are well-known, a large nut that shells well with bright kernels, and the most consistent yields of any widely-planted cultivar. The preference beginning in 2012 by Chinese buyers for this cultivar made the nuts very valuable relative to most others. A major and often overlooked advantage for Desirable is that it is not as susceptible to aphids or sooty mold as most cultivars. In addition to scab susceptibility, disadvantages include weak limb structure and susceptibility to pecan leaf scorch mites. Be aware that there is great risk in wet seasons of substantial crop loss on a cultivar this susceptible because of inability to get sprayers in the orchard when the orchard floor is too wet. Recent research by Clive Bock would lead to the suggestion that hedging Desirable to reduce tree height would enable shorter trees, making it easier to spray tops of trees, and can reduce scab risk. This hedging approach should be considered by those with Desirable trees in scab-prone sites.
USDA (Mohawk x Starking Hardy Giant) Type 1. 55 nuts/lb. 54% kernel. Another cultivar we conditionally recommend, at least for trial, is Pawnee. The nuts of Pawnee are highly valued because of the early harvest date, about Sept. 20, large size, and excellent quality when managed well. Pawnee is very scab susceptible, but scab is not as difficult to control as on Desirable. Good growers willing to spray, irrigate properly, crop thin, hedge, and fertilize properly can produce excellent yields and quality on Pawnee. If overloaded, or not managed well, quality can be poor and alternate bearing very severe. Pawnee is intolerant of crowding, more so than most other cultivars. This cultivar, like Desirable, is suited only to growers dedicated to intensive culture.
There are many other cultivars with good or outstanding characteristics but with poor scab resistance. Because of the devastation of this disease and the high risk, we do not recommend planting them. These include Sioux, Nacono, Western, Wichita, Morrill, Byrd, and Cunard.
Additional information, and color pictures of these selections, can be found at the Alabama Pecan Growers Association website. http://alabamapecangrowers.com/cultivars.html
Goff is Nunn Bond Professor and Extension Pecan Specialist- Emeritus for Auburn University, and a pecan grower with orchards in Georgia, Alabama, and Mississippi.
Photos of Excel from University of GA Pecan Breeding program
Photos of Lakota, Kanza, Elliott, Sumner, Apalachee, Creek, and Desirable from USDA Pecan Breeding program