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12.14 Micro-budded, High Density Citrus Planting: Is There an Opportunity for HLB
Control and Financial Returns?
Skaria M. and Hanagriff R.D.
Texas A&M University-Kingsville Citrus Center, 312 N. International Blvd, Weslaco, TX
Micro-budded citrus: In the mid 1990s, a technique called micro-budding was developed to
bud small citrus rootstocks (4,6). The rootstock used was approximately 2 month-old sour
orange. Several hundred small, micro-budded citrus trees were planted in a field (3x6 ft), over a
6 month period. Some of the scions were only ½ inch long, but most had scion growth 6 inches
or more when planted. The trees performed well and many had fruit in 1999 – 2 years after
micro-budding. One Rio Red grapefruit tree produced 19 fruit. These trees are still alive. This
process is unique in that 1) micro-budding by-passed the nursery phase, 2) produced scions
smaller than conventional trees suited for ultra-high density planting and 3) trees developed early
bearing. Although viewed as innovative and attempted by some nurserymen, micro-budding was
not widely adopted, due to unfamiliarity of budding small plants. However, some researchers
have made successful use of micro-budding (3,5) and in 2005, a private nursery in Edinburg,
Texas successfully produced micro-budded trees commercially. All plants are growing well in
the nursery and in orchards.
One year-old micro-budded plants in the field
2-year-old Marrs
orange
Micro-budded and planted
Small
rootstock (by passed the nursery phase)
Scion growth
Weeks after planting
2-year-old Rio Red grapefruit
Figure 1. Stages of micro-budded, ultra-high density planting started on June 11, 1997.
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Example of a Florida Valencia Orange Return: The following graph illustrates the net return
from Valencia sweet orange planted in 1991, at a tree density of 250 trees per acre. After
planting with conventionally budded trees, the first four years had zero income (2).
Net $ Return/Acre
2500
2246.3
2000
In Florida
1500
882
1000
2006
2005
2004
140
2002
0
1995
0
1994
0
1993
1992
0
1991
0 0
1999
500
1996
U.S $
1616.5 Hurricanes
Figure 2. Net return from Valencia trees on Swingle citrumelo rootstock planted in 1991,
Charlotte County, Florida. Data Source: Mongi Zekri, IFAS, UF, with permission. Revenue
based on $2.87 (1996) and $2.65 per Kg solids. Pick and haul highest cost $2 per 90 lb box.
Figure 2 above shows that net dollar return from a typical high density orchard with 250 trees per
acre, using conventional trees is not high. Under HLB and psyllid pressure this level of net
income will be insufficient to sustain the additional cost of HLB management. Therefore, every
effort to combine all promising avenues of HLB management strategies should be explored
including more efficient psyllid control and the use of high density or even ultra-high density
orchard design with precocious trees of reduced tree cost . Planting a high density of microbudded trees will offset the initial planting cost of an ultra-high density orchard. The
precociousness of micro-budded trees assures more rapid economic returns.
Ultra-high Density orchards: Fruit yield and the net economic return to growers in the early
years of an orchard are directly related to the number of trees per acre (7,8,9). In the past, all U.S
citrus producing states have experimented with high density orchard planting as a means to
increase fruit production and profitability. A small number of growers successfully practice high
density citrus operation, some even ultra-high density but the majority of U.S citrus growers
were reluctant to adapt the high density practice. Though fruit yield in high density orchard is
higher in early years, most growers are not willing to change the field equipment or to pay a
higher cost for more trees per acre. It has come to a reality that the US citrus growers have to
adapt alternative strategies to counter the impact of HLB. An approach now under consideration
is to produce citrus on a high density, short-term cycle. The idea is to push early production,
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adopt efficient chemical, cultural, and biological control strategies to reduce the psyllid
population and HLB infection.
Net Present Value (NPV) comparison: NPV is a time value of money technique that discounts
future streams of projected net profits using an opportunity cost of money rate (also referred to as
a discount rate) to determine a single present value of future profits. The cost of conventional
high density planting and micro-budded, high density planting can then be subtracted from
current value of future profits, which results in NPV. A positive NPV number communicates
additional income above opportunity cost and planting cost. A negative value communicates a
poor capital budgeting decision. Also, a higher NPV communicates the best capital budget
decision with the differences in the values representing value differential. Capital budgeting also
can utilize Pay Back Period, which is the year(s) it takes profits to repay initial planting cost as
well as Internal Rate of Return (IRR) to measure the average present value of returns over the
initial investment. This capital budgeting tool was applied to both micro-budded high density
(565 trees) and conventional planting (150 trees) as described by Roka and Rouse (9). There is a
slightly higher initial investment cost, but financial returns far exceed the expense and microbudded HD method of production provides potential economic efficiencies of land use and
higher return on investments. This method of productions needs application testing, but even
partial results have high financial returns.
Today
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Year 7
Year 8
Year 9
Year 10
Conventional, 150 trees/acre
Revenue Cost
Net
Payback
$
$
$
$
0
1,950
4,650 -4,650
0
750
-750
-5,400
1,387
1,000
387
-5,013
1,677
1,000
677
-4,336
2,632
1,000
1,632 -2,704
3,742
1,000
2,742 38
3,930
1,000
2,930 2,968
4,922
1,000
3,922 6,890
4,810
1,000
3,810 10,700
4,776
1,000
3,776 14,475
4,499
1,000
3,499 17,974
Micro-budded high density, 565 trees/acre
Revenue Cost
Net
Payback
$
$
$
$
Today
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Year 7
Year 8
Year 9
Year 10
0
0
5,223
6,318
9,913
14095
14,802
18,540
18,117
17,988
16,947
1,978
1,000
1,500
1,650
1,650
1,650
1,650
1,650
1,650
1,650
1,650
-4,978
-1000
3,723
4,668
8,263
12,445
13,152
16,890
16,467
16,338
15,297
-4,978
-5,978
-2,254
2,414
10,677
23,122
36,274
53,164
69,631
85,969
101,266
Table1. Conventional planting with 150 trees and micro-budded, HD cost and payback
compared.
The NPV for high density planting is estimated to be $68,037 per acre compared to the NPV
from conventional planting of $8,293. There are also an estimated 18 % higher returns and a pay
back of the initial investment two years ahead of the conventional planting.
Possibilities with micro-budded trees: The cost of production of micro-budded trees is
approximately ⅓ of the conventional system. This allows the grower to plant more trees per acre
and to harvest more fruit per acre in the early years. Approximately 4X more trees may be
planted for the cost of conventionally budded trees. The precocious nature of micro-budded trees
enhances early fruit production.
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Negative aspects of micro-budded trees and possible mitigations: In order to fully utilize the
benefits of micro-budded trees, they should be planted young in an orchard setting. This makes
them more vulnerable to psyllids and thereby to HLB infection under Florida conditions. In
Texas, smaller trees are vulnerable to wind and browsing by jackrabbits. However, intensive,
ultra-high density planting can be coupled with more efficient use of systemic insecticides such
as imidacloprid to protect the trees. There are ways to protect small trees from wind and
browsing. The newly tested open hydroponics (OHS) and the new Florida model of advanced
production system (APS) combined with micro-budded ultrahigh density planting may make it a
worthwhile approach to pursue under HLB and psyllid pressure in Florida. A revolutionary
control strategy is required to counter the Florida HLB problem. Micro-budded, high density
citrus orchards may offer some benefit to the growers in Florida and elsewhere.
Citations
Skaria M. 2008. 11th International Citrus Congress, Wuhan, China, October 26-30.
Zekri M. 2008. International Citrus Congress, Wuhan, China, October 26-30.
Ochoa FM, Dekkers MGH, Skaria M, Lee RF. 2000. Proceedings of the International Society of
Citriculture 9th Congress 2000. p.583.
Skaria M, Tao Z. 2000. Proceedings of the International Society of Citriculture. 9th Congress
2000. P 584.
Yang ZN, Ingelbrecht IL, Louzada E, Skaria M, Mirkov TE. 2000. Plant Cell Reports 19: 12031211.
Skaria M. 2000. Proc. 14th Conf. IOCV. IOCV, Riverside. p. 411-413.
Boswell SB, McCarty CD, Hench KW, Lewis LN. 1975. J. Amer. Soc. Hort. Sci. 100: 370-373.
Roka FM, Rouse RE, Muraro RP.1997. Proc. Fla. State Hort. Soc. 110:82-86.
Wheaton TA, Castle WS, Tucker DPH, Whitney JD. 1978. Proc. Fla. State Hort. Soc. 91:27-33.
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