Pecan Challenges for Southwest Texas

     Before growers look for the "pot of gold" at the
end of the rainbow in their pecan orchards, they need 
to remember that a total management program is 
required for year in and year out production of 
quality pecans. The management program begins at 
planting as 50% of the production potential of the 
orchard has been determined once the orchard has 
been planted.  So if one does a poor job at planting, 
either from site selection or the physical planting 
of the trees, the production potential of the orchard 
will have been reduced.
     The number one underlying factor related to 
the success or failure of the orchard is soil.  
The better the soil, the better the trees will 
perform regardless of the management program.  A
well rounded management program can then only help
to make things better.  However, if the soil is
poor, often times even our management program, no
matter how good, cannot overcome such deficiencies.
     Still, even with the best soil in the world 
on which to grow pecans and a complete management 
program, without sunlight the orchard will never
perform.  It is absolutely critical that all 
parts of the tree continue to have light as the 
tree grows in order to be most productive.  This 
means trees must be planted on a wide spacing or
they must be thinned as the limbs begin to touch.
     Another critical aspect of pecan growth and 
development which is often overlooked is air.  
Without adequate air in the soil, the roots cannot
function to pick up water and/or nutrients.  It 
may be that future research tells us that running 
aeration equipment is as important as applying 
nitrogen.
     Once things are right from the soil, light 
and air perspective and a complete management 
program is in place, the greatest challenge pecan
growers have is to grow a large crop of leaves 
and hold them in a healthy, functioning state 
until frost.  Sometimes it is easy to grow them 
but to maintain them is another question.
     Some years, early feeding from thrips 
absolutely destroys the unfolding leaves and 
severely limits their photosynthetic capacity.  
Other years phylloxera can destroy a lot of leaves
which again reduces the food manufacturing 
potential of the trees.  It is critical that we 
not lose the first crop of leaves or even that it
not be less (in size and functioning capacity) 
than normal.  The trees will either have to expend
"new energy" to regrow the leaves or it will have 
to make do with less.
     We have apparently made the full circle in 
terms of sprays on pecan trees.  Many growers used
to apply an insecticide with the other products 
such as zinc or a fungicide every time they were 
spraying. Today we have moved to a more cautious, 
almost hate to spray and/or spray as needed 
attitude, which is good.  However, in certain 
years we may have to look hard at budbreak 
insecticide sprays to help insure the growth of 
nice big healthy leaves early in the season.  Many
years the first flush of leaves which come out 
really look bad.  So, if we could grow big, 
healthy leaves from the start, we may help our 
trees a whole lot.
     Water seems to be the key to one's management
program.  The water has to be right to make all 
the other things fall in line.  Mature orchards 
require 8 to 10 gallons per minute per acre of 
trees in order to produce quality pecans.  The 
key is to wet the entire root zone and hold the
water in the top 2 to 3 feet of the soil.  
Ideally, this water should be applied every 3 
weeks and possibly more often.
     Water stress to the trees prior to shell 
hardening will cause some of the nuts to shed.  
Water stress after shell hardening causes the 
leaves to shed instead.  Without leaves, no food
is made and the kernels will not fill.
     The major fertility elements which are 
required by pecans to maintain healthy growth 
continue to be nitrogen and zinc.  No doubt, the
others are important as well, but generally there
are adequate amounts present in the soil.  If not,
they would be required as well.
     Finally, to date most management programs 
have lacked specificity to variety.  All 
varieties have been treated the same as far as 
nutrition, water and some sprays have been 
concerned.  Since all varieties have distinct, 
unique characteristics, we need to address our 
management programs to each individual varieties'
needs.  Gone are the days when we fertilize all 
varieties the same across the board. Needs should
be based on the characteristics of the soil, 
geographical location, crop load and/or 
environmental conditions.  Also, each variety 
will need to be managed to take care of only the 
specific insect or disease pests which plague 
that variety.

Barton		   Desirable          Pawnee            Stuart
Cape Fear          Kiowa	      Schley            Success
Cheyenne           Mahan	      Shoshoni          Western
Choctaw            Mohawk	      Sioux             Wichita




     Wichita - most productive variety in terms 
of dollars earned, probably also the most cussed 
variety; very consistent yearly production when 
given ample space or good sunlight, good 
fertilization -- minimum 150 lbs actual N, 6 zinc
sprays and water -- late season water a must to 
reduce vivipary; tends to form weak tree crotches 
-- requires extra training; prone to freeze injury
if overcropped; early harvest generally required;
shell hardening is early, so early shuckworm 
control required; susceptible to scab; kernels 
turn dark fast, need to harvest early and move 
them or place in cold storage; early female flower
receptivity requires early pollen shedding variety
such as Caddo, along with a traditional 
protandrous variety such as Cheyenne.


     Western - San Saba seedling -- hence, strong
vigorous growing tree; productive variety which 
makes a good pollinator for Wichita; very 
susceptible to scab and should only be grown in 
the west; low management variety but still 
productive -- 120 lbs actual N, 3-4 zinc sprays;
quality is fair to good but shells well.
     

     Cheyenne - excellent quality pecan with 
super eating quality; consumers who know Cheyenne
will ask for and demand it once they are familiar
with it; willowy tree with small leaves, hence, 
training to a central leader can be difficult; 
very susceptible to yellow aphids -- minimize
insecticide use, ie. only spray when absolutely 
necessary; casebearer should not be major 
concern; most serious pest other than aphids is 
shuckworm and/or weevil, leaves tend to be 
smaller than other trees -- hence, early zinc 
sprays are essential -- minimum of 5 required;
150 lbs actual N per acre per year required; late 
season water essential for nut fill; water, soap 
and/or KNO3 sprays may be required to disrupt 
aphids; heavy crops and sooty mold will promote 
alternate bearing.
     

     Pawnee - although too early to know for sure, 
looks very promising; the tree is very upright 
growing with strong vigorous limbs and dark green
foliage; however, it is slow to come into 
production; the nut matures very easily and hence 
shuckworm has been a big problem on this variety, 
growers must cut nuts and spray at 1/2 shell 
hardening - this could be as early as mid-July 
with a follow up 10 days to 2 weeks later; there 
has been some tendency to alternate bear so 125 to 
150 lbs N/acre are recommended with 5 to 6 zinc 
sprays; the variety has some yellow aphid resistance
 - not immune but less aphids than other varieties; 
harvest will be early (mid-September) so early 
predator control a necessity; excellent potential
as a gift pack variety.
     

     Desirable - to date one of the most 
overlooked varieties in new plantings; has name 
recognition and market sales but requires patience 
to come into production; limbs tend to break out 
as a young, fast growing tree; 5 to 6 zinc sprays 
are required with 125-150 lbs N/acre; tree tends 
to have light green foliage and an ugly tree 
(bare limb) appearance; early tonnage is low but 
pecans produced are of top quality; most of the 
nuts Desirable matures are of top quality due to 
nut shedding by Desirable to reduce its crop load; 
many other varieties outyield Desirable but when 
you compare quality nuts per se, Desirable is 
right on the money; requires ample space and light 
for maximum production in future years.  Pecan nut
casebearer and hickory shuckworm must be 
controlled since this variety needs to retain as 
many nuts as possible due to light yielding 
characteristic.
     

     Choctaw - has the potential to be the highest 
quality pecan grown or one of the worst; requires 
deep well drained soils for optimum results; do 
not plant Choctaw if you have 3 feet of soil or 
less - ideally this variety would have 8 to 10 
feet of soil - the better the soil the better the 
variety will do; fertilization and water management 
are absolutely critical for production of this 
variety, management of these 2 variable will 
somewhat overcome shallower soils but it will 
become exceedingly difficult as the trees get 
older; 150 to 175 lbs actual N per acre is required 
for best results; 6 to 7 zinc sprays are in order; 
water is critical to both size and fill out this 
pecan - do not plant without irrigation, design 
system to wet entire orchard floor in later years 
with a minimum of 2 inches per week; nut tends to 
have a week suture so early harvest is essential 
to prevent losses to fire ants and such; also early 
harvest is necessary to maintain the nice bright 
kernel color; one of the later varieties to break 
bud in the spring - a characteristic of its Success 
parentage; tends to have a fairly high number of 
pops - another of its Success traits.  Casebearer 
can help Choctaw trees by thinning nutlets during 
heavy crop year.  An average of 3 - 3.5 nuts/cluster 
is desirable for Choctaw trees.
     

     Kiowa - has the most leaves of any variety 
- hence, early and frequent zinc is absolutely 
essential; minimum of 8 sprays required; large
nut which requires an abundance of water for best 
quality, probably requires more water than most 
varieties; heavy rain in '92 promoted good kernel 
quality, fuzz is common on the kernels of stressed 
nuts; 150-175 lbs actual N per acre required; 
smaller nuts tend to have better quality than
larger pecans; tree will tend to overcrop and 
then alternate bear, hence casebearer may help 
thin this variety; only spray casebearer if minimal
crop.  Benlate important at water stage to reduce 
stem end blight; leaf scorch can be a problem on 
this variety - Orbit  seems to control this if
management program is adequate; freeze damage has 
been a problem on this variety since it is such a 
vigorous grower - fails to slow down in the fall 
many years; cultivation promotes zinc deficiency 
on this variety.  As many as 8 zinc sprays and 175 
lbs actual N/A may be required for optimum results; 
late season water an absolute must in August, 
September and October for high quality kernels. 


     Sioux - one of the most beautiful trees for 
an improved variety; strong central leader growth 
with wide branch angles -- hence, minimum training 
required; tree tends to have lots of leaves -- 
early zinc required, 4-5 sprays for best results; 
nuts are small but of high quality, kernels tend 
to crack when shelling so perfect halves are 
difficult to obtain, however, quality is 
outstanding; 125-150 lbs actual N/A required; some 
problems with sticky shuck -- Benlate at water 
stage tends to reduce but not prevent; rare for 
limbs to break and/or trees to overbear.


     Shoshoni - a very fast growing and 
precocious variety which tends to grow straight 
up; tends to form a central leader with little or 
no training; variety is prone to crop heavy early 
sending the tree into alternate bearing; a lot of 
the tree food reserves tend to go into wood 
production and hence the tree and nuts are 
stressed in a heavy crop year, resulting in poor 
quality.  Quality is good initially but tends to be 
poor later; requires 125-150 lbs N/acre and 4 to 5 
zinc sprays; nut thinning is required on this 
variety to produce quality pecans consistently, 
casebearer should not be controlled in heavy crop 
years.  An average of 3 - 3.5 nuts/cluster is 
desirable.  The major use of Shoshoni should be 
as a temporary tree.


     Mohawk - produces one of the most beautiful 
trees grown - long recommended as a yard tree due 
to its dense foliage with large leaves; today not 
recommended as a backyard tree because of the large 
shucks (ie., it is messy).  It is very difficult to 
grow as a commercial variety; it produces a very 
large nut which is very difficult to fill out as 
the tree gets older - an attribute of its Mahan 
parentage; requires high rates of nitrogen, 
150-175 lbs N/acre and several zinc sprays, 5 to 6 
to increase the possibility of nut fill; tree will 
alternate bear heavily if allowed to set and mature 
a heavy crop of nuts; thinning is critical to 
reduce alternate bearing and increase quality; 
water is critical in late season to fill out the 
nuts - minimum of 2 inches per week in August and 
September; nuts have thin shells which makes 
mechanical harvesting difficult; tends to ripen 
early though - early harvest required to maintain 
light kernel color; casebearer should never be 
controlled on this variety if it has a crop; 
shuckworm control critical for nut quality.  
Mohawk is not recommended in Texas.


     Mahan - has made many growers a lot of money 
because of its large nut size; quality becomes poor 
as the tree gets older; requires good soil plus 
heavy nitrogen and water applications to improve 
quality; makes a beautiful tree probably because 
it is a Schley seedling; 150-175 lbs of actual 
N/acre recommended along with 5 to 6 zinc sprays; 
water is critical in August, September and 
October for nut fill, late maturing variety so 
requires long-term management; casebearer should 
never be controlled in crop years and shuckworm 
control is necessary to increase nut quality; nut
thinning would be desirable in heavy crop years.  
Not recommended in Texas.


     Barton - was the first variety released from
the USDA pecan breeding program; originally it 
tended to have very good all-around qualities, 
however, with time, it has lost productiveness 
and quality; requires good zinc spray program with 
at least 6 applications; 125-150 lbs actual N per 
acre required; thinning may reduce alternate 
bearing tendencies on overloaded trees; casebearer 
should not be controlled in heavy crop years.
Barton is no longer recommended.
     

     Schley - is an old variety that produces an
outstanding quality pecan; probably a Stuart 
seedling - hard to believe you can get something 
this good out of Stuart - which is a very pretty 
spreading tree; probably was named for its bearing 
characteristic - ie. sly bearer, fails to produce 
high tonnage; very susceptible to sticky shuck 
and/or SEB (stem end blight); Benlate required at 
water stage to reduce this problem, tends to be 
worse some years; variety matures late in season 
so late season water - August, September and 
October critical to nut fill; 125-150 lbs actual 
N/acre required with 5 to 6 zinc sprays.


     Cape Fear - is apparently a Schley 
seedling; again one of the easiest trees to train; 
develops a central leader naturally with wide, 
strong branches surrounding the trunk - virtually 
no pruning required; tree is slow to come into 
production but produces a high quality, light 
kernel, requires 125-150 lbs actual N per acre 
with 5 to 6 zinc sprays; water critical late to 
fill out nuts; good management program is required
to reduce alternate bearing tendencies, nut 
resembles Stuart but is much higher in quality.


     Success - an old variety which can produce 
high quality pecans; a major fault is shuck 
dieback which leads to many pops; this is a 
physiological problem caused by the constriction 
of the peduncle which attaches to the nut; one of 
the last varieties to bud out in the spring; 
requires 125-150 lbs actual nitrogen per acre and 
6 to 7 zinc sprays for best results; tree is prone 
to show zinc deficiency if sprays are lacking;
late maturing nut so water management is critical 
in August, September and October; nut quality is 
really outstanding on good nuts; late shuckworm 
can cause problems on this nut since it matures 
so late.


     Stuart - another seedling variety, hence 
upright vigorous growing tree; very slow to come 
into production but fairly disease resistant; nut 
quality is much better in Texas than in the 
southeast; variety is a fairly consistent producer 
once it comes into production and a management 
program is maintained; 125-150 lbs actual nitrogen 
per acre is required and 6 to 7 zinc sprays; tree 
is prone to show zinc deficiency if zinc sprays are 
lacking; matures late season so late season water 
necessary to fill out the kernels.  Not 
recommended for Central Texas.
     
     In summary, our challenge is not only variety 
management, but also to properly manage dwindling 
sunlight in some orchards.  We have to react and
take trees out before we have lost production.  
Our objective is to concentrate on a distinct 
program for each variety of which utmost importance 
is the crop of leaves on the trees.  Obviously many 
folks have been doing this due to the number of 
repeat crops in the state.  However, as with 
anything, nothing is constant and our programs 
will have to continue to change to meet the crop's 
demands.






For more information contact:


Larry Stein
Texas A&M Research Center
1619 Garner Field Road
Uvalde, Texas 78801

PHONE:  (210)278-9151 Ext. 134
FAX:    (210) 278-4008
E-MAIL:  larrystein@tamu.edu

TAMU, Uvalde