Arapaho Citrus Management, Inc.

Transcription

1 Overall Impression Arapaho Citrus Management, Inc Okeechobee Road Fort Pierce, FL The Latt Maxcy Group of Groves By Peter D. Spyke Citrus Consultant October 25, 2012 The current management team is doing a very good job. The trees look exceptionally healthy, particular the resets, which are very difficult to grow due to HLB (see Appendix 1 for a complete discussion of HLB, or Citrus Greening). They stay ahead of problems, and the crops on the trees are good. The fruit production, combined with the proposed fruit contract, will ensure a profit into the future (see spreadsheets). Therefore, the challenge is to derive the best strategic approaches that will maximize profit over the next 10 years, so this report focuses on some of those considerations. Miracle Springs Grove as good as it gets. Medium density grove, 100 % canopy coverage, well maintained. The interaction of the management team and the grove sites are capable of achieving this level of performance. The locations of the groves include some of the very best sites for citrus production in Florida. While not all groves are performing to the maximum possible, the potential afforded by the sites create the opportunity of achieving consistently aboveaverage production. This is an important consideration. The industry-wide costs and returns will always seek a level where an average operation can make enough profit to stay in business over the long term. If for the same cost, the production of fruit per dollar spent is higher due to the superiority of the site, the long term net revenue has the chance to exceed the average. 1

2 The sites are all clustered in the southern part of the citrus belt in locations that are not prone to freezing, as evidenced by the presence of trees that are 40+ years old in all the groves except those that were planted more recently. The water supplies are adequate, and the drainage is good. The soils are among the best, so all these factors combine to reduce risk. With the higher profit potential and lower risk, this grove operation is the best opportunity that could be imagined. The challenge will be to manage the operation by making strategic and tactical choices that lead to a long-term positive performance in spite of any environmental or market challenges. In my opinion, that outcome is very likely with this operation. The citrus groves can be segregated in a number of ways to sharpen the focus on strategy for each group. The first basic distinction is Ridge vs. Flatwoods. Within those two major categories, the groves can be further grouped as to variety, tree ages, canopy volume, and other criteria that would determine the best approach for management of each group. Ridge vs. Flatwoods Fruit-laden branch on a replacement tree that is about 6-8 years old in Lake Buffum. Bearing efficiency is a measurement of the amount of fruit per unit of volume in the tree canopy. The bearing efficiency of the variety/rootstock combination and the tree size, expressed as % canopy coverage per acre, determine the yield of the trees. In Central Florida, a ridge of rolling land with very sandy soils runs from just south of Lake Placid up into Georgia. Within the climate zone suitable for citrus, the Ridge as it s called has proven to be an excellent situation for citrus production provided that a good irrigation system is used to supply water to the trees during periods of low rainfall. In the deep sands, the roots of the trees will penetrate more deeply into the soil profile, which improves water and nutrient uptake. Consequently, groves on the Ridge have the highest yield per acre, largest trees, lower costs, and are better able to withstand environmental challenges. In the central Ridge area, the groves are generally older, dating back to the 1950 s when the technology for producing frozen concentrated orange juice (FCOJ) was developed and a flurry of planting followed as a result. 2

3 Trees planted on the rolling well-drained soils typical of Florida s Central Ridge can grow to a very large size filling the space allowed even with wide between-row spacings. Replacement trees grafted on rootstocks that impart tree size control will not reach the size necessary to achieve a high percentage of canopy coverage per acre in this situation. The Coastal Plain lies on either side of the Ridge. The land is very flat, and the soils are poorly drained. The native vegetation would be slash pines and cypress, which leads to the name Flatwoods. Typically, the water table during the summer rainy season is close to the soil surface, and periodic flooding is common. Citrus does not like wet feet, so in order to produce citrus, the land must be bedded and drained. The higher water table during the summer rainy season limits the depth of rooting, so the trees tend to grow more slowly and produce less fruit per acre for any given variety and rootstock combination, but the fruit usually has higher pounds solids per box due to the more moderate vegetative growth rates. In the past, rootstock choices were different for the Flatwoods, with rootstocks preferred that tolerate flooding and the higher soil pathogenic fungus intensity common in that situation. Much of the intense relocation of citrus that followed the freezes of the 1980 s occurred in the Flatwoods, particularly in Southwest Florida. Ridge groves in the northern citrus belt were abandoned, and large drainage projects allowed development of citrus in the Flatwoods areas. Groves planted on Flatwoods sites must be bedded and drained to allow citrus production. This adds some costs for maintenance of the drainage system components, and limits the production of the trees due to restricted rooting area as compared to the Ridge. In the Latt Maxcy groves, Backbone, Frostproof, Moeller, and Rawle are all Ridge groves. Lily, Island Pond, Chancey Bay, Ranch One, and CPI would all be considered to be Flatwoods groves. 3

4 The Ridge Groves Group The greatest opportunity to generate higher marginal income over the next 10 years lies with the Ridge Groves Group. The upside potential of the rest of the groves is less than with these blocks. Therefore, extra attention should be paid to maximizing the economic performance of these groves, because the possible gains are the greatest. Typical range of tree size in the older groves. The largest trees are the originals, and have grown to the size upon which the 60 tree/acre orchard geometry was based. Replacement trees on the right are 6-10 years old, while those on the left were recently planted within the last few years. To attain maximum canopy coverage without changing the between-row spacing, replacement trees will need to be on rootstocks that promote larger tree size. With a few exceptions, the Ridge groves were originally planted in the mid-1900 s. The original trees were mostly processed orange varieties, and the tree spacing was wide to allow room for the trees to grow large, because commercial hedging and topping equipment was just being developed. Tree spacings of 25 in the row x 30 across the middles were common, which is about 60 trees/acre. On the virgin land, the growers used rootstocks that impart high vigor so that the space allowed for each tree would be completely filled. Trees up to 30 tall required very long ladders for harvest. Trees on these rootstocks, though, tended to be more short-lived than trees on rootstocks that grow at a more moderate rate. This has required almost a continuous replanting program for the past 30 years. In the processed variety blocks, trees of the same variety have been reset to facilitate harvesting, but the rootstock choice has varied over the years as rootstocks move in and out of favor with production managers and owners. Starting in about until last year, trees infected with HLB were removed in the subject groves. So, in addition to natural attrition, this led to Site of recently-removed tree, prepared for replanting. Trees can be spaced more closely within the row to increase the density and canopy coverage within reason, with wider spacing for more vigorous trees. 4

5 a high percentage of the available tree spaces occupied by newly-planted resets. Of the remaining trees, most of them are not original, so are resets from prior years as well, often on rootstocks that impart low or moderate vigor. As a result of all these factors together, the canopy coverage in many of the Frostproof blocks is low, which has resulted in relatively low yields per acre as compared to the potential of the groves. Canopy Coverage: This is an intuitive concept that has been adopted by some as being a major focus of management, particularly the South African growers who tend to use a very structured approach to managing citrus groves. The basic philosophy is that 100% Canopy Coverage is achieved when the trees on an acre of grove land have grown to the maximum size allowable, and must be maintained at that size with pruning. Maximum yield can only be achieved when the canopy coverage reaches 100%, because regardless of variety and rootstock, a bigger tree will always produce more fruit than a smaller tree. Aerial image of the Rawle grove. Trees in block on right have grown to fill the space allotted to them and are maintained at that size with pruning, which is defined as 100% canopy coverage. The block on the left has a mixture of tree sizes, from large original trees to newly-planted resets. Looking from above, the large amount of bare ground is evident, a low percentage of canopy coverage. The between-row spacing is wider on the left, so each tree will have to be larger to approach the ideal 100% canopy coverage level that is necessary for maximum yield. The average yield of the Frostproof group ranges from about 150 to 500 boxes per acre. The higher the % canopy coverage, the higher the production per acre. In most of these groves, 100% canopy coverage will probably never be reached, however, because of the rootstocks used for resets that were planted more than 6 years ago. Moving forward, the choice of rootstocks for 5

6 resets will become the single most important factor that determines the profitability of these groves in the future. Rootstocks: Commercial citrus rootstocks have a wide range of attributes, including disease resistance and effect on the vegetative vigor and precocity of the trees. For example, Valencia Oranges grafted on Rough Lemon rootstock will be trees that grow quickly and produce fruit with relatively low internal quality, whereas Valencia on Carrizo Citrange will produce a medium sized tree with very high quality fruit, and Valencia on Swingle Citrumelo will be a smaller tree that is more precocious (more fruit per cubic foot of canopy), and the fruit will be of medium quality, but the trees will be very long-lived. The bud union (the grafting technique used for citrus is called budding ) is the site of the graft between the variety that is used, or the scion, and the rootstock, or stock. This photo of a Valencia Orange on Carrizo Citrange shows the bud union about 6 inches above the soil surface. There many rootstock varieties available. Many of the common rootstocks are hybrids of a citrus relative, Poncirus trifoliata (Trifoliate Orange), with other varieties of oranges, grapefruit or mandarins. Poncirus parentage provides some degree of dwarfing and higher precocity. However, these hybrids tend to be sensitive to soil conditions, and have certain susceptibilities to soil-borne pathogens and parasites. Older rootstocks are simply varieties chosen for their attributes, such as Sour Orange, Rough Lemon, and Cleopatra Mandarin. Newer rootstocks are simple or complex hybrids between two or more varieties. At this point, there are options that impart varying degrees of vigor and precocity, but only two rootstocks, Carrizo Citrange and Swingle Citrumelo, are the most used in the industry. Kuharske is a selection of Carrizo that is purported to have better resistance to burrowing nematodes. Although a few trees in the groves have been planted on Cleopatra Mandarin, most of the resets are planted on either Carrizo or Swingle, with the The Hurd orange trees in Lily are easily some of the oldest commercial trees in Florida. The rootstock is unknown, but has imparted a long life while achieving a large tree size and good productivity. 6

7 predominance of the most recent replants being on Carrizo or Kuharske. While these are certainly time-honored conservative choices, there are drawbacks to this approach, particularly with regard to the impact on canopy coverage. Changing the spacing between rows requires complete removal of every tree in the block and replanting them using closer row spacing. Since all the groves have existing productive trees, continuing to replant using the existing row spacing is the best approach. For example, many of the Ridge groves, and Island Pond, are planted with at least 30 feet between the rows. Modern row spacing is feet between rows, so it s not possible to add a row in between. Therefore, moving forward, the existing between-row spacings will have to be retained. The trees in each of these pictures are spaced about the same in the row, and are roughly similar in height, but the distance between the rows is about 30 feet on the left in Cannon 1, and 19 feet in the Rawle block on the right. The canopy volume per tree is similar, but the canopy volume per acre is a much higher percentage on the right. To achieve the same percentage, each tree on the left will have to grow to a much larger size to close up the middle. That s why it s important to choose the variety and rootstock according to the space the trees will occupy, as much as other factors such as disease resistance, etc. It is possible to plant the trees more closely in the row, and to a certain extent this will happen as widely-spaced original trees are replaced with two or three in an attempt to regenerate the lost canopy volume as quickly as possible. Trees on a low-vigor rootstock such as Swingle Citrumelo can comfortably be planted very closely, but the problem is that these smaller-sized trees will not grow sufficiently large to fill all the available space between the rows. So, the issue is not tree count per acre, it s the distance between the tree rows that will limit fruit production per acre regardless of the spacing in the row. Almost 60% of the trees in Frostproof are less than 4 years old, and the majority of these are on Carrizo Citrange rootstock. In many blocks, the percentage is even higher because other blocks, such as Miracle Springs, have almost no missing trees. Carrizo is a solid choice that will eventually produce a large tree, but the trees grafted on Carrizo tend to start off slowly and gain momentum only after year 5 or so. Diversity can be a good thing, so it is strongly recommended that evaluation of alternative rootstocks should be initiated. The primary objective would be to find rootstocks that lend 7

8 themselves well to these unique circumstances. The ability to grow a large tree quickly should be the primary criteria, with the consideration of the precocity of the trees being a secondary consideration because regardless of the inherent bearing efficiency, higher canopy coverage will result in more fruit. There are many alternatives available, including legacy stocks such as Rough Lemon, and new USDA hybrids. These will all be special order trees, so more The reset program will determine the long term profitability of the Ridge groves more than any other single factor. The management team is doing an excellent job of growing healthy young trees. lead time would be required for the nursery supplying the trees. Of particular interest for Valencias would be US 802, Volkamer Lemon, Macrophylla, Milam, and Rough Lemon. For Early-Mid varieties with inherently lower internal quality, high-vigor rootstocks can result in fruit quality below minimum standards, so although Carrizo may remain the best choice, additional alternatives should be tested, including X639, US812, Sun Chu Sha, Furr (C57), and Benton. While the ultimate tree size may not be larger than Carrizo, trees on these rootstocks may grow off more rapidly. There are some trees of Vangasay Lemon in Banks and Sparks that should be evaluated critically as well. The large tree on the right may cost more per box to harvest than the smaller tree on the left, but the additional boxes would more than outweigh the added cost. If rootstocks that impart high vigor are chosen, new reset trees should be planted further apart in the row as well to allow each tree to maintain a more natural shape. Note that this approach is directly counter to the prevalent philosophies concerning rootstock selection in the citrus industry today, which is to use rootstocks that produce compact and highly precocious trees. In the case of these Ridge groves, however, the wide between-row spacing precludes the high density goal of new plantings. The space that must be filled by each tree is inherently larger, so the sooner the trees fill that available space, the faster the production will approach the theoretical maximum afforded by 100% canopy coverage. So, the best strategy to use may be similar to that of the original plantings 50 years ago. 8

9 The only drawback would be with harvesting. It s more expensive to harvest tall trees, and mechanical harvesting may be difficult. However, the additional cost for hand harvesting would be more than offset by higher production, and these groves are not good candidates for mechanical harvesting anyway because of the variability in tree size, so more boxes per acre should be the predominant goal. Fresh Fruit Rootstocks: Many of the fresh fruit blocks in the Ridge group are being converted to processed blocks by replanting lost trees with processed varieties, which is probably a good strategy. In this case, the above rootstock selection criteria should be considered since most of the between row spacings are wide. However, if the original fresh variety is to be retained, then fresh fruit resets should be grafted on rootstocks that impart high internal fruit quality, even if the trees won t grow as large. Under no circumstances should any fresh fruit variety ever be grafted on Swingle Citrumelo because the internal fruit quality is too low to command premium prices from the most exclusive markets, and in this case the trees wouldn t grow large enough to approach maximum canopy coverage. Sun Chu Sha, X639, and any of the Citranges would be better choices. Segregation of the Ridge Groves: Lake Buffum, Miracle Springs, Hill Home, Old Barn, and a few other small areas in groves have a high percentage of canopy coverage, so the production levels are the highest in the group. The fresh fruit blocks in Briggs and Story are also relatively strong. For the remainder, the canopy coverage is probably less than 50%, so the yields are also less than half the potential. These are the blocks where the most attention and effort should be devoted to develop the best strategy to increase the canopy coverage as rapidly as possible. The Flatwoods Groves Group The market price for fresh fruit such as these Lee Tangerines in Briggs is based on the appearance and internal quality of the fruit. Rootstocks should be chosen to promote the highest possible brix (sugar) levels and juice content, which will lengthen the harvest window and increase value. There are really two groups of Flatwoods groves Lily, Island Pond, and Chancey Bay, and Ranch One and CPI, because the groves in the former are self-managed, while the latter two are managed by an outside company. 9

10 Lily is in a good situation for the Flatwoods, with fine-textured soils and good drainage capabilities. The average production is about 350 boxes/acre, although the best producing blocks produce almost 600 boxes/acre, which indicates the potential of this grove. Most of the between row spacings are 30 feet, so the high production blocks are characterized by a predominance of very large trees. Lily is a victim of the bad neighbor situation regarding HLB, where surrounding growers Lily is technically a Flatwoods grove requiring supplemental drainage, but the site has better natural drainage and soil texture than the other Flatwoods groves, so production can be higher. Much of Lily will require heavy resetting due to losses from HLB and other causes. did not respond as aggressively to control psyllids and remove infected trees, so HLB losses were apparently more significant. This makes the reset strategy even more important. Lily has a bit of an advantage because since it is a flatwoods grove, the low internal quality with vigorous rootstocks will be moderated to some extent. Island Pond has a lot of character, and in its heyday was one of the best groves in Florida. The site is exceptional, which is to be expected when there was so much land to choose from. The original trees were mostly on Sour Orange rootstock, and they were spaced wide and allowed to grow to a very large size, which resulted in phenomenal production per acre of very high quality fruit, so the pounds solids per acre were probably as high as would ever be possible. Unfortunately, trees on Sour Orange rootstock are susceptible to an Many of the original trees on Sour Orange still remain. When one is lost, it takes the resets many years to replace the production of each of these very large trees. insect-vectored virus disease called Tristeza, and with the introduction of the Brown Citrus Aphid, an efficient vector, in the early 90 s, the disease spread more rapidly. A series of freezes resulted in additional tree losses, and then the CBC eradication program forced the removal of 10

11 large areas of trees entirely. Consequently, there are already a lot of resets in Island Pond, and the original trees in the undisturbed blocks will continue to decline and require replacement. So, once again, the reset program will have a very strong influence on the future performance of the grove. Murcott (Honey Tangerine) trees in Island Pond. The original varieties are being maintained rather than converted to processed orange varieties, a good choice due to the higher internal quality of the fruit when grown under Flatwoods conditions. All of the rows in Island Pond are 32 feet apart, including those in the solidset new blocks. Therefore, to achieve the maximum possible production, resets on size-control rootstocks of any kind should be avoided because the trees will never grow wide enough to fill the space between the rows. Cold tolerance is more of an issue, though, than in Frostproof, so the very vigorous stocks such as Volkamer and Rough Lemons may be too cold sensitive, although if they are damaged, they recover more quickly than trees on other stocks. Part of Island Pond is still flood irrigated. While this is perfectly acceptable for the older trees, it makes establishment of resets more costly since they must be hand-watered until they are large enough to respond to the seepage effect of flood irrigation. Therefore, if the reset percentage climbs too high in these blocks, it may be preferable to install a low-volume irrigation system. For example, an inexpensive drip system may be less expensive than growing off a large number of resets without supplemental irrigation. With the flood irrigation ability, any cold protection afforded by microsprinklers is less important, so a drip system would be a very feasible alternative. Citrus Bacterial Canker in Island Pond: While the fruit lesions caused by CBC (Citrus Bacterial Canker) are not so much of a problem on processed fruit varieties, severe infestations can cause defoliation and fruit drop. For fresh fruit, the fruit lesions are grade-lowering factors, so control must be nearly absolute. Citrus varieties vary in their susceptibility to CBC. Generally, Hamlins, Midsweets, and Vernia oranges are more susceptible than Pineapple and Valencia, although Pineapples can be overwhelmed, too, 11

12 Localized infestation of CBC on Midsweet in Island Pond block with sufficient severity to cause defoliation. CBC is very difficult to control, which is why the eradication attempts were justified. under certain conditions. CBC can infect newlyexpanded citrus leaves just by coming into contact, but anything that wounds the leaf, with leaf miners being the predominant cause, will allow the bacteria to infest otherwise resistant leaves. With older leaves that are not injured, CBC can infest the stomata on the underside of the leaves if driven in by wind-blown rain at wind speeds greater than about 20 mph. Therefore, two measures are the most important to keep CBC levels in processed oranges below economic levels, which are leaf miner control, and windbreaks. Of the two, the leaf miner control is generally the source of epidemic level infection rates, but windbreaks can greatly reduce the likelihood that CBC will spread from infected trees to less infected areas. In Island Pond, the blocks that were replanted after their removal during the CBC eradication program were replanted on the original beds. The blocks were originally engineered with ditches every six rows that run parallel to the tree rows to provide a water supply for volume gun irrigation. Since the new blocks were converted to microsprinkler, these ditches were refilled with the spoil on site, but not planted with Citrus Leafminer damaged leaf after becoming infected with CBC. Citrus Leafminer wounds allow CBC infection in otherwise resistant leaves when moisture is present. citrus trees because the areas are not well drained. When touring the grove, Tom Powers remarked that these unplanted areas would be a good place for windbreaks, and I agree wholeheartedly, particularly in the blocks that have more susceptible varieties. Ideally, the blocks should be divided into about 10-acre segments, which 12

13 would be about 660 x 660. If the windbreak trees grow to 60 feet tall, they would reduce the wind speed in the block sufficiently since the effect is about 10 times the height of the windbreak. To attain 60 foot tall windbreaks, 2 rows would be best, one with Eucalyptus grandis, and the other with Corymba torelliana. Finally, because of the CBC severity in Island Pond, consideration should be given to restricting future replanting to Valencias, which is much less susceptible than other varieties. Obviously, this would not be the case in existing blocks, but would be an option in complete replacements or conversions. Chancey Bay has had a tough life over the past 8 years, with hurricanes, freezes, floods, and HLB affecting the health of the trees. While not yet fully recovered, it s coming back. Chancey Bay is a more recentlyplanted block, and is a classic Flatwoods grove. Everything is bedded and irrigated with microsprinkler, and the row spacing is 30 feet apart average. The only thing unusual is the configuration in which two trees are planted closely together and irrigated with a single microsprinkler, with wider spacing between the two-tree groups. The grove looks good, though, so it apparently works just fine. HLB hit the Martin County Flatwoods groves particularly hard, and Chancey Bay is one of only a few groves that eventually survived at all. The credit goes to the fact that it s somewhat isolated from other commercial groves or areas of dooryard trees, and the aggressive approach by the management. In spite of these efforts, the infection rate from HLB is the highest of any of the groves, which has reduced production. Some areas were replanted after losing trees to water damage using the two trees/microsprinkler planting scheme unique to this grove. There is a comparison in place that includes three different foliar nutrient treatments to determine the best way to restore the trees to full Typical HLB-infected tree. The disease has been very severe in this area. 13

14 Heavy pruning, as in this test row, has shown to improve HLB recovery in severely infected trees. productivity. After about 3 seasons, it is apparent that one of them is doing the best job, so it may be advisable to terminate the experiment and just treat everything with the best combination. The top of bed spacing in Chancey Bay is narrower than 30 feet (the spacing across the water furrows is wider), so the need for fastgrowing rootstocks isn t as acute as with the wider-spaced Ridge groves. However, in the blocks originally planted with Carrizo rootstock, Blight and HLB losses have been higher, so there are a lot of open spaces, and will be more in the near future. Rootstocks such as X639, Benton, and Sun Chu Sha might be considered as alternatives to reduce the reliance on only Carrizo and Swingle. Both of the latter have limitations in Flatwoods situations, and other stocks may be superior in the long run, and would fill the empty spaces faster. It should be noted that production gains from Chancey Bay will be moderate, although they will definitely occur as HLB treatments improve and more resets are planted and begin to contribute. The potential gain, however, is much less than in the Ridge Grove group. Ranch One and CPI are both under agreements concerning the management of the groves, and fruit marketing. At this point, the management is still removing infected HLB trees, so theoretically the remaining trees are healthy. However, they are also using a nutritional supplement program designed to mitigate the effects of HLB in infected trees, so the cost is as high as for infected groves. The two blocks in the Cooperative Producers planting are both Valencia on Swingle Citrumelo. The canopy coverage is high, but the production isn t as heavy as would be expected. More research into this situation may be helpful. The individual owner cannot adjust the programs. The only option is to add additional treatments or materials to the programs they are using. So, the owners cannot decrease the intensity of the programs, only increase the inputs. 14

15 The exception is the choice of resets. Currently, there are areas in Ranch One where tree losses have been higher than normal due to Blight, combined with about a 5% average attrition rate from HLB infected tree removal. The management team is replanting with Swingle and Carrizo, the primary rootstocks used down there for the original groves. The trees on Swingle are not declining as fast as those on Carrizo, which is to be expected. However, even when the blocks were at their peak, the production per acre was less than would be expected from full-grown trees at that density. It is presumed that the shortfall in potential is not due to management, and the trees appear to be healthy, so the most likely cause is the rootstock choice. Both Swingle and Carrizo perform well in Flatwoods situations with finer-textured soils and good drainage, but they both can be affected in other situations to the point where fruit production is diminished. Neither can even be used at all on the East Coast in situations similar to Rootstock trials such as this one in another grower s block in CPI, and in Ranch One, may provide guidance for rootstock selection in the future. Ranch One and CPI. The trees did grow well and have reached containment (100% canopy coverage for original trees), but the precocity is apparently compromised somewhat. Excellent block of Valencia on Carrizo in Ranch One. The canopy coverage is at a maximum, although further yield increases are probable due to improved cultural practices adopted as a result of HLB. applied as results become available. So, as with the other groves, the rootstock selection for resets should be seriously studied. Fortunately, rootstock trials have been planted at Ranch One in previously vacant areas that will provide very good information that can be X639 may be a good candidate for these two groves, particularly if there is any salt in the well water used for irrigation. X639 has proven to be the most salt tolerant of all the rootstocks, and has many good attributes. So, it should be seriously considered. Fortunately, the owners do have the ability to determine the reset program in their groves. Unusual phenomenon in Ranch One. The grove was developed in the western Everglades, and the climate is apparently warmer and more humid, so trees have a layer of moss and ferns coating the northern side of the limbs. 15

16 The big advantage in Ranch One and CPI is that since they are still on a tree removal program for HLB, it s easier to grow off a reset. Because the young trees flush more often than older trees, they re more attractive to psyllids, particularly when flushing off cycle from the old trees. Since in these groves the psyllid control is good and the HLB inoculum is low, resets will grow normally without taking the extreme measures necessary in other areas. This will allow replacement of lost canopy coverage when original trees are lost more rapidly, thereby preserving yields at a higher level. Other General Considerations Variety Choices: At this point, all processed orange varieties appear to be affected by HLB to about the same extent. Valencias, though, are much less susceptible to CBC, which will reduce costs. They also have higher brix, which allows a wider choice of rootstocks. They ripen after the winter, as opposed to Hamlins that ripen in the late fall, but the groves are mostly in locations that minimize freeze risk (only Island Pond and Lily are in areas that tend to be colder), so Valencias would get the nod for the preferred variety. New varieties are under development that have various positive attributes, including HLB and CBC tolerance. The University of Florida and USDA have breeding programs devoted to citrus, and a new entity called the New Variety Development and Management Corporation (NVDMC) has been established to facilitate introduction of new varieties from Florida, California, and other countries. Tropicana has also commissioned breeding programs with UF, and there are currently field trials of new varieties that Tropicana will patent and control. It is certain that the industry will migrate toward new varieties that mitigate risk and increase profit. The relative position of a company will be determined by the extent to which they participate in the process. Recent policies have been approved by UF and the NVDMC that will facilitate testing and introduction of promising new variety candidates, and it is strongly recommended that full cooperation be given to this program. At some point, the ability to plant new varieties will be restricted as to both participants and allowable acreages, so it will be very important to participate in the early evaluation in these grove situations to be able to make judgment decisions about participation in later phases of the introduction process. Grove Care Programs: As more is learned about HLB and CBC, management will be able to sharpen their choices as to inputs to minimize the impact of those two diseases, while continuing to perform the other necessary programs. Historically, grove care activities have been segregated into 7 major programs: Spray Program Weed Control and Middles Management Irrigation and Drainage Program Nutrition Program Pruning Program Reset Program General Grove Activities 16

17 Harvesting is normally considered to be independent of the core grove management program, but does require a significant investment in time and resources as well. Parts of the HLB and CBC control programs will be distributed among all 7 of the grove care programs. The current management team is doing a good job of making the necessary adjustments. Further study will be ongoing, and additional modifications to control costs while improving the effectiveness of control will no doubt occur. Harvesting: In the past, most of the citrus was hand-harvested by migrant laborers. Many of these were not legal, but the system was incapable, or unwilling, of achieving reliable compliance. The issue is gaining importance, though, as immigration policies become political topics. The practice in the past was to use harvesting contractors to supply the labor, with the grower not being responsible for verifying immigration status. More recent legal rulemaking has led to the position that the landowner shares the liability for illegal immigrants, even if they are not in their direct employ. This has encouraged growers with larger acreages to find a less risky way to ensure the labor supplies necessary to harvest their crops. The current best alternative is the H2(a) program, in which groups of workers are allowed entrance into the country to perform specific jobs during certain periods of time. Agriculture is the largest user of this program, although other industries utilize it as well. Things are a bit more complex under H2a because housing and transportation must be arranged. Most harvesting contractors don t have the resources or credit rating to support this level of financial commitment, so the large growers generally have to take some shared position. The Latt Maxcy group currently uses H2a workers, and this direction should be continued until the immigration policies become more refined. The availability of harvesting workers has become especially critical during the Valencia season, when alternative easier and higher-paying jobs are available in Blueberries and other crops. Since the long-term strategy may be to increase the percentage of Valencias in the variety mix as discussed above, this is an important consideration for these groves. Risk Management: Much risk has been mitigated by distributing the groves over a wide area, which minimizes the likelihood that any single event would affect all them to the same extent. Additional risk management is normally built into the grove management and harvesting programs. Crop and Tree insurance has become an important consideration as well. It requires a lot of study and preparation to choose and obtain the best level of coverage, and if an event occurs that results in a potential claim, the need for support of the insurance representatives is acute. The costs of the Crop and Tree insurance can be considerable, and the policy requirements are extremely complex. So, sufficient resources should be devoted to doing a good job of managing this important activity, since the assistance received after losses is considerable. 17

18 Summary Conclusions Unless something completely unexpected occurs, the groves should produce enough fruit within the next 10 years to ensure a profit under the terms of the proposed contract. The management team has proven their ability to make good choices, and have responded to the recent challenges better than most other organizations, and they are to be commended. Moving forward, the primary constraint to profit will be the relatively low fruit production per acre in many of the Ridge groves, and Lily. There is an opportunity to modify the reset program to increase the fruit output per acre within the 10 year term of the contract above what it would be with the current approach at virtually no additional cost, or risk. It will require research and study, as well as testing in the field, so the sooner the process can begin, the better. The chances of overall yields consistently decreasing are slim. There will be annual fluctuation, so the outcome will not be the straight line result shown in the accompanying spreadsheets, but the trend should be close to what is shown for the first few years. After year 6, the outcome will depend on the choices made in the tree removal and replacement program. Management has control over most of those choices, however, so a positive approach should produce favorable results. ************************** Appendix 1 Huang Long Bing (HLB), also known as Citrus Greening The bacterial disease Huang Long Bing (HLB), also known as Citrus Greening Disease, was discovered in commercial citrus groves in Florida in It was first observed in commercial groves in China about 125 years ago, and has since migrated to many other areas, usually by movement of infected plant material. HLB is spread from tree to tree by the Asian Citrus Psyllid (ACP), a small insect that feeds on the leaves of the tree with piercing-sucking mouthparts. The HLB Bacteria can survive in the gut of the insect long enough to be introduced in salivary secretions when feeding occurs. The Asian Citrus Psyllid had been present in Florida for a number of years prior to the discovery of the disease, and the feeding of the insect only causes minor effects in the trees. It s the ability to spread HLB that presents the greatest problem from the ACP. Isolated foliar symptom of HLB on a tree in Miracle Springs. The trees receive treatments that mitigate the effects (see next image). HLB is a phloem limited bacteria. In the wood and twigs of citrus trees, the center woody part is the xylem, and the layer of bark is the phloem. The HLB bacteria live in the phloem, which is where most of 18

19 Even though many trees are infected with HLB bacteria, nutritional supplements and ACP control have allowed management to maintain the trees in a healthy, productive condition, such as these in the same area of Miracle Springs. the transport of photosynthetic carbohydrates occurs. As the bacterial multiply, they plug the cells in the phloem, thereby interfering with the transport, which causes the trees to gradually decline in vigor. The fruit produced on HLB trees is small, very bitter, and green in color the source of the term greening. The bacteria have no effect on anything other than citrus, so there are no health issues to anything other than the trees themselves. Prior to the discovery of HLB in Florida, growers in other countries had learned to deal with the disease by removing infected trees, thereby reducing the inoculum, and controlling the ACP. If all the growers in an area cooperated, it has been possible to continue successfully in the citrus business in the presence of HLB. Florida s citrus industry has a number of attributes that makes this approach difficult, including large areas of concentrated citrus plantings, multiple owners, some of whom are absentee or otherwise not directly involved with management of their properties, a predominantly processing variety industry, and most ironically, a very highly developed Integrated Pest Management equilibrium. In regards to the latter, many of the indigenous or introduced insect pests of citrus have been controlled by traveling around the world to places where citrus species and the pests have coexisted for millennia, and finding natural enemies of the pests that keep them under control naturally. By capturing, rearing, and releasing these natural predators to Florida, the industry has been able to control the major pests without topical pesticide applications. This complicated the HLB situation because growers didn t normally have to spray the trees very often. In the case of processing varieties, only CHMA s have allowed citrus growers to utilize aerial application of materials to control ACP. The industry was under-equipped to respond with ground spray equipment when HLB was first discovered, leading to the rapid spread. one or two spray applications per year was sufficient to maintain profitable production levels in the groves. The Asian Citrus Psyllid and CHMA s : To control the ACP, multiple applications of insecticides are required during periods of leaf flushes to push the pest population low enough to 19

20 slow the spread of HLB. It has to be almost complete, because even 90% control leaves enough psyllids to spread the disease. Ranch One and CPI are in the Gulf CHMA, which assists growers with coordinated control of ACP. Valencias are highly attractive to ACP, and no feeding damage was observed, so the program is successful. So, when HLB was found in Florida, the industry did not have sufficient capabilities to control the spread of the disease enough to successfully combat the disease by removing infected trees and controlling the ACP. Some growers with large contiguous properties responded quickly, and have been able to keep infection levels below the 5% maximum necessary to use the tree removal approach. For most growers, however, tree removal and ACP control slowed the spread for a while, but if they had neighbors who were not doing the same, or insufficient equipment, the infection levels eventually built to the point that tree removal was no longer a rational choice. In other countries, growers had success with coordinated efforts to control ACP. For example, I observed valleys in China planted in citrus where all the individual growers, of which there were many, would spray for ACP on the same day. Scouting would determine the timing, and this concerted effort was very successful there was very little evidence of ACP in the groves. When in South Africa, growers there confirmed that they worked together to control ACP, and once again this helped reduce the spread of HLB. In Florida, the Florida Cooperative Extension Service and the Florida Department of Agriculture Division of Plant Industry have joined with growers to establish CHMA s, or Citrus Health Management Areas. Within a CHMA, the two agencies assist growers with planning pesticidal sprays to control ACP, and where the growers have all cooperated, the program has been successful. Costs are lower, and control is better. Isolated groves such as Island Pond don t need to be in a CHMA since there are no other groves in the vicinity. For the other groves, CHMA s will greatly assist with HLB management. Nutritional Sprays: While the industry was transitioning through the HLB response process, some growers began experimenting with different production practices intended to prolong the productive life of infected trees if removal was no longer an option. It was observed that applications of nutrients to the foliage appeared to alleviate some of the symptoms of the disease, and slow the decline. Further research clearly indicates that the trees can be maintained indefinitely, and when selective pruning is added, even trees in decline can be rejuvenated. At this point, the nutritional treatments for HLB are basically a kitchen sink approach in that the sprays contain mixtures of virtually every nutrient a tree might need. Further work is underway to isolate the nutrients that are the most important, and to find the most economical rates. At this point, though, it has become an accepted fact that it will be possible to produce 20

21 wholesome fruit for the processing industry and maintain good tree health even though the trees are infected with HLB. Eventually, research will find ways to combat HLB without external inputs. The most promising line of work are the intense efforts to find antimicrobial peptides, which are snippets of DNA that impart resistance to bacteria naturally. Anti-microbial peptides exist that can make citrus resistant or tolerant to HLB, but they are from other organisms, so they are not viable options since the fruit would be labeled as a GMO (genetically modified organism). However, as the genetic sequences of the anti-microbial peptides are determined, there is the possibility that similar DNA may exist somewhere within the citrus plant family that can eventually be introduced into commercial varieties through traditional plant breeding techniques that would avoid the GMO classification. There is reason to believe this kind of mechanism is realistic, since there are citrus varieties out there that are not affected to the same extent as others. This is a long-term solution because it will take years to perfect the genetic modifications, and then multiply, plant, and grow the new trees. In the meantime, the nutrient treatments are proving to be the successful alternative. The Subject Groves and HLB This tree in Lily was identified as being HLB infected prior to the cessation of pushing infected trees. It is not fully recovered, but is responding to foliar nutritionals and should continue to improve, but at present is somewhat compromised, and susceptible to stress. This points out the need for plant material that is tolerant of the disease. As a whole, the groves show less effect from HLB than most others in Florida. The management team decided to remove infected trees early, and continued until They began treating the trees with nutritional sprays quickly after the initial evidence indicated that it would help. Most of the groves are in CHMA s or isolated so that the in-house ACP control measures are sufficient to maintain very low populations of the insect. Consequently, the trees appear to be very healthy, and for the most part are producing at or near their maximum potential. More importantly, the newly-planted trees are growing well, and are not showing significant HLB symptoms. 21

22 Grove care costs have significantly increased due to the additional foliar sprays necessary to apply the nutrients and control ACP. Recent research has indicated that it may be possible to adjust the spray formulas and/or timing to reduce costs somewhat. Therefore, the modeling does not anticipate significant, rapid escalation of grove care costs. On Resets: The skill that management is showing at growing young trees is important. Not everyone has been successful at resetting. In most cases, the trees can be maintained in good health for about 3 years. Later, when they are fully mature, production can be maintained with the nutritional sprays. Between the ages of 4 and 8, however, it has been very difficult to grow trees normally if they become infected with HLB. If the growth rate slows due to HLB during these years, the trees can become stunted, and may never reach full size, which will limit the canopy volume of the block. The ability to grow trees of this age opens alternatives for rootstock selection. If there is a need to recover canopy volume rapidly, one technique is to use rootstocks that impart more vigor to the trees, regardless of the variety. The downside is that the increased vigor makes it more difficult to control ACP, since there are more vigorous growth flushes each year, and the trees may outgrow the beneficial effects of the nutritional treatments. So, it is the success of the current team at managing these factors that opens up options that may not otherwise be feasible. Resets between the ages of 4 and 8 years of age, such as this tree in Lily showing mild HLB symptoms, are the most difficult to protect. The management team is doing a good job, but infected trees were removed until last year. In the future, this may prove to be more difficult, although good ACP control through CHMA s will help in the effort. All opinions expressed are the author s alone. Projections of future events are inherently uncertain, and no guarantee express or implied is made as to the actual outcome of events. 22