The news out of Florida seems to continue on the not-so-good side. First, there were two trees (one news report claimed half a dozen trees) in Dade County confirmed as having the Asiatic strain of citrus greening disease. Greening is a bacterium (Liberibacter asiaticus) that is primarily transmitted by psyllids.

The symptoms of greening are similar to severe nutritional deficiencies, with yellowing, dieback, mottling of older foliage, and tree decline. The fruit is often of reduced size, lopsided internally, and usually inedible due to poor taste-if it doesn't drop before maturity. Diagnosis is not easy-suspect samples must be subjected to a series of polymerase chain reaction tests that can confirm or deny the diagnosis.

The discovery of greening was not entirely unexpected, as state and federal officials anticipated that possibility when the Asian citrus psyllid vector was first detected in the U.S. at Delray Beach, FL, in June, 1998-so they have been on the lookout for it since that time. Just so you'll know, the insect has been in Texas for the last two or three years.

Note: Since the above was written early in September, state and federal officials in Florida have confirmed a number of cases in the area and several miles to the north. Obviously, the fears are that greening is more widespread than originally suspected, which lessens the odds for containing it before it appears in commercial groves. Among other difficulties in combating this disease is that the bacterium can be present in only part of the tree and may not produce visible symptoms for up to 3 years.

At about the same time, a stem-pitting form of citrus tristeza virus was detected on a lime tree in Dade County. Florida has always had milder versions of tristeza, but the stem-pitting strains are considered somewhat more severe.

If all of that wasn't bad enough, Waverly Growers Cooperative, one of Florida's top 20 packinghouses, announced that it will not open its packinghouse this or next season because of inadequate fruit supplies to meet its basic fixed costs of operation. The Coop is in Polk County, which is under heavy commercial development pressures (and several citrus canker finds). Waverly's grower members have sold over 700 acres of citrus to developers in the last year or so, with close to that much under contract for closure in the next year or so.

Last season, Waverly shipped only about 575,000 cartons, about half the volume it shipped in 2003-04. Fortunately for the approximately 90 grower-members of Waverly, Haines City Citrus Growers Association (also a cooperative) has agreed to accept their production for at least the next two seasons. Haines City CGA itself lost over 1,000 acres of production to development in the last year and a half.

When you look realistically at Florida, the hurricanes of last year were certainly a major problem for the citrus industry. However, the continued spread of citrus canker?in large part also due to the hurricanes-is having a major impact, as the loss of an orchard to canker is perhaps more devastating to growers than the loss to a major freeze. In the latter case, the grove can be rehabilitated or replanted immediately, but a grove lost to canker sits idle for two years.

Then factor in the phenomenal urban pressures to build-build-build. Subdivisions are taking over many prime citrus areas, with the attendant need for additional land to house the services those people need, which in turn requires even more land for housing for the folks who move in to work in those service industries.

And I guess the same thing is happening to citrus families as has been happening to other families that have traditionally been involved in agriculture, the younger generation just isn't much interested in continuing what the parents or grandparents started. The world is bigger than the couple of hundred acres of orange trees that granddaddy so-and-so planted back in ought-whatever.

Then factor in the economy. Citrus, like most of agriculture, is facing hard economic pressures-in no small part because of higher costs of production in the U.S. as compared to foreign countries (and that, in turn, significantly due to labor costs). Net returns to growers often are less than the same investment would make in interest income from CDs or government bonds.

So, what's a grower to do? Frankly, just what they are doing-hang on as long as possible, then sell out to developers when the price of the land is too high to ignore. And the price of grove land in Florida is up in the five-digit range. As a case in point, under the formula that was developed to reimburse growers for trees lost to canker, the price ranges up to $9,000 an acre, and the grower keeps the land (whether Congress ever appropriates that money has yet to be determined). If the price for a grove gets that high in Texas, you can certainly count me among those former growers who sold out and retired.


The official crop forecast will be released by the USDA on October 7 (I think), so you'll soon know how close the guesses are. There are already some estimates out there for Florida's crop. Louis Dreyfus Citrus predicts 207 million boxes of oranges in Florida; Elizabeth Steger is not far away at 206.6 million.

Officials with Southern Gardens' 32,000 acre-operation in south Florida are not so optimistic, suggesting only about 180 million. Reasons cited are the continued losses to canker (Southern will reportedly lose about 4,000 acres to canker before harvest starts) and the observation that fruit size has never been this small for the time of year.


September brought some rain, but the amounts were far short of so-called ?normal? or average for the month. Maybe October can make up the difference, but that could delay harvest.

There was little relief from the high temperatures that we have been under for so long, can you believe triple digits in late September? While fall officially arrived around the autumnal equinox of September 21, I can assure you that fall in south Texas does not recognize a calendar date.

News over the weekend is that Mexico made good on its commitment to fully erase their water debt by September 30. As of now, the debt that reached about 1.5 million acre feet at one time has now been eliminated. The final included some in-reservoir transfer of ownership as well as some inflows from the six tributaries named in the Water Treaty of 1944. The inflows were not releases from storage-they were simply from rainfall that occurred below the dams on those streams.

There is a lot of back patting going on, but a few locals point out that, while it is nice to have the debt resolved, they are concerned that little has been set in stone in terms of preventing the problem from recurring in the future. Yes, current levels in the reservoirs are good, though not at full capacity, but that can change a whole lot sooner than you think.


Because of delays and weather and other factors, my vine control is still a work in progress. However, I will relate what I have found to date. The important products with which you may not be familiar are discussed first.

Rivet is a siliconized methylated seed oil from Agriliance. I did not have a non-silicon MSO to test initially-the only reason I mention that is because Rivet is somewhat more expensive than straight MSO. Too, I used Rivet at 3% and 6%, whereas its label calls for 0.75% for ground application and 2% for aerial application. Consequently, I don?t know if a lower rate of Rivet or any rate of straight MSO would provide the same results.

LandMaster is a combination of Roundup and 2,4-D from Monsanto. For those concerned about using 2,4-D, I would point out that this material is labeled in Florida for citrus, which suggests that it should be possible to obtain a special local needs registration in Texas, should it become desirable. According to my calculations, a 2.5% solution of LandMaster is equivalent to 1% 2,4-D and 0.75% Roundup.

Morningglory vine. In tests this summer, 2% Roundup with 3% Rivet made it sick but did not kill it. However, 2.5% LandMaster with 3% Rivet provided total kill of treated vines on the ground beneath the tree. In addition, Solicam at 3 lbs per treated acre prevented all germination of morningglory seed-there was no germination in the Solicam-treated area, but plentiful seedlings came up adjacent to the treated area. Hyvar X at 3 lbs was inconclusive as was Princep at 3 lbs (there was no germination of morningglory seed inside or outside the treated area).

Goatsbeard vine. In tests this summer, 2% Roundup with 3% Rivet killed it, as did 2.5% LandMaster with 3% Rivet. I cannot make any claims about pre-emergence control using either Hyvar, Solicam or Princep, as there were no goatsbeard seedlings that germinated either inside or outside the treated area.

Milkweed vine. In tests this summer involving only milkweed vine that was running along the ground, not going into the trees, 2% Roundup with either 3% or 6% Rivet took awhile, but it looks like it has finally killed it, as there is no evidence as yet of regrowth. In addition, 2.5% LandMaster with 3% Rivet worked beautifully, providing total kill within about a week, with no apparent regrowth. In terms of pre-emergence control, there have been no germinations either inside or adjacent to the treated areas, so I cannot make any claims there.

Possum grape vine. This one is still a little tough to call. The 2% Roundup plus either 3% or 6% Rivet made it very sick within just a few days, but I am not yet confident that there will be no regrowth-only time will tell. The 2.5% LandMaster plus either 3% or 6% Rivet made it very sick within a few days and appears to have killed the treated vines (they were broken off below the canopy two weeks prior to treatment). However, I am not yet confident that there will be no regrowth. In terms of pre-emergence materials, there are some apparent germinations in both the Hyvar X treated area as well as outside, as is also the case with Solicam. The operative word here is "apparent"-as I am not totally sure whether these are germinations or regrowths. I intend to carefully excavate some of these to try to determine if they are from seed or from the underground storage organ.

Providing these results to you should in no way be considered any kind of endorsement of the materials and rates used, inasmuch as these results are still preliminary and must be repeated. In addition, other work is still in progress with different MSOs and different rates. Moreover, LandMaster is not currently labeled for use in Texas citrus. Finally, it may be necessary to obtain seed of these vines to do in vitro germination tests using some of the different pre-emergence herbicides that are labeled for use in Texas citrus, as it is not always assured that there were seed present in the test areas.

Professor & Extension Horticulturist
2401 East Highway 83
Weslaco TX 78596


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