AUGUST, 2010      

VOL. 24, NO. 8                                                                             






Another line from Credence Clearwater Revival’s “Bad Moon Rising” foretold of excess water. The second line after “I hear hurricanes ablowing” is “I fear rivers overflowing”, which they did.

While Hurricane Alex went inland over 100 miles south of the Valley, it and a subsequent Tropical Depression dumped untold amounts of rainfall over the mountains of northern Mexico.  Much of the area where the rains fell is part of the overall watershed for the Rio Grande River and the runoff quickly started to fill the dams on all of the tributaries in Mexico, which then started to fill Lake Amistad and Falcon Lake on the Rio Grande. 

Because lake levels were already pretty high, the International Boundary and Water Commission opened the gates and discharged very high volumes of water into the river.  The Amistad releases, along with inflows from tributaries in Mexico that enter the river below Amistad, combined to create serious flooding in Laredo and points further upstream early in July.  These waters ultimately made their way into Falcon, which was also quite high already, as did waters from other tributaries in Mexico that flow into Falcon (Rio Sal being one).  Consequently, the gates at Falcon were soon opened to high discharge rates, which have continued through the end of July.

Inflows into the Rio Grande from tributaries below Falcon Dam added to the total volume of water coming downstream.  Diversions into the Floodway at Anzalduas Dam near Mission soon filled it to capacity.  All unharvested crops inside the Floodway were lost.  There are some orchards and crops between the Floodway and the River south of McAllen/Mission that went under water as the River spread out (no levees at that point) and have basically been underwater for several weeks. 

The Floodway has held and done the job it was designed to do—prevent widespread flooding of cities along the River as well as other parts of the Valley.  It isn’t perfect, however, as not all of the gates that regulate local drainage water entry into the Floodway have the best of seals, so there are places that have become flooded because of backflow leakage from the Floodway into the drainage ditches and canals.  There have been reports of seepage through the Floodway levees, but I’ve seen no official confirmation of that.

All low water crossings of the Floodway and the Arroyo Colorado have been closed since early July and will remain closed until the Floodway finally drains into the Laguna Madre.  As of this writing, the Floodway level at the Expressway crossing in Mercedes has finally begun to go down.  At peak flows, the water level was only about a foot below the railroad trestle, but that gap has now increased to about two feet.  Don’t take these numbers to heart, as my estimates were made at 65 mph while crossing the bridge.

Given the excess waters coming down the system, the Valley was fortunate that the heavy rains that were forecast with the Tropical Depression that followed Hurricane Alex did not materialize.  Other rains that threatened during July simply did not turn into major concerns.  Because the drainage gates into the Floodway were closed, most of any surface runoff from the Valley’s farms and cities would have had no place to go.  Hidalgo/Cameron County Irrigation District Number 1 spent a lot of time and money pumping eastern Hidalgo County drain waters over the levee into the Floodway, but heavier and more widespread rains probably could not have been accommodated.


As one consequence of last month’s discourse on the grapefruit juice pool closing, a question was raised about how “value added” applies to Texas grapefruit juices.  The short answer is that while a great deal of our grapefruit juice is sold in bulk as concentrate and as single strength, a significant portion is canned/bottled for retail sale.  It is these latter sales that are value added. 

Because of Federal mandates regarding the WIC program, canned juices are giving way to bottles.  To that end, TCX spent millions last year to install a PET line to be able to continue to supply juices to WIC and other programs.  Cans aren’t entirely gone, but they may not be around too much longer.

As a side note, unlike grapefruit juice, the Valley’s orange juice is almost entirely value added, as there is almost no sale of bulk concentrate. Unfortunately, because of poor color and low acidity of Marrs orange, which provides the majority of our processed orange juice, TCX has to buy about as much Valencia solids as all the solids we produce to blend to make a saleable product.  With few exceptions, Valencia solids cost more than solids of early-and-mids.


Rains in July slowed grain and corn harvest, but drying conditions finally allowed harvest to proceed.  Citrus has benefitted from the increased soil moisture—the summer flush is maturing and fruit is sizing better than in most seasons at this time. 

Rust mites are everywhere, but growers seem to be keeping them in check.  Psyllid sprays were initiated for the summer, but there are reports that their numbers are building.  Untimely weed control has resulted in a proliferation of weeds in groves, but drying conditions are such that growers should be able to knock them out before too much longer.


Citrus greening continues its march northward along the west coast of Mexico with recent reports that the disease has been identified in the southern part of Sinaloa state.  That brings the total to four states on Mexico’s west coast, leaving only Sonora as a buffer between existing greening and Arizona.  While that is alarming, bear in mind that Sinaloa is a long state (north to south), so the disease and hot psyllids have a long way to traverse yet.

Lest you not be terribly concerned about the northward advancement along the west coast, you should appreciate that an awful lot of produce comes into the US from Sinaloa.  Moreover, one of the main overland routes from Mazatlan, Sinaloa is across Espina del Diablo to Durango, then north to Chihuahua (and El Paso) or east northeast to Torreon, Coahuila and to Monterrey, Nuevo Leon.  From there, it’s only a short hop to Laredo or McAllen.

Meanwhile, on the Yucatan Peninsula, there has been no official change in the status of greening—both hot psyllids and positive trees have been detected in Quintana Roo, Yucatan and Campeche, but has not yet spread beyond those states into Tabasco or Vera Cruz.


Under conditions of a CHRP grant from USDA to Texas AgriLife Extension, we have the responsibility to provide what might be called Super Master Gardener training in three locations upstate, i.e., veteran Master Gardeners were selected/volunteered to receive an intensive two-day training in citriculture (one day) and citrus insects and diseases (one day).  A number of us traveled to Rosenberg last week to conduct the first of these events.  There were 32 veteran MGs from a number of surrounding counties and I would have to say that it was one of the most fun events in which I have been involved in recent years, as it was a great crowd of excited and interested folks—which always encourages good speakers.

Aside from the 16 hours of classroom training, attendees will have to perform two of three volunteer service projects.  The first is mandatory—collect and submit to diagnostic testing tissue and/or psyllid samples from eight different locations in or near their home county. 

The second is one of two optional efforts—assist the CEA to plan and carry out a four-hour educational clinic to identify common insect, disease and nutritional problems of citrus in the county.  The other option is to carry out a research demonstration to ascertain the effectiveness of freeze protection methods for citrus in the home landscape during two or more potentially damaging freeze events.

I don’t much care for the latter option, even though it is fairly detailed, because of the simple fact that cold protection projects have a pre-requirement for the occurrence of freeze events—and who knows what the coming winter might bring.  Besides, I am really more interested in the greening work, as that was the basis for the grant and the educational programs—to teach these folks enough about citriculture and citrus pests and diseases to enable them to do a better job of being on the lookout for citrus greening in urban areas upstate.


While I was in Rosenberg, I received word that sweet orange scab (SOS) had been detected in the Spring area of Northwest Houston.  For those of you who don’t know, there are two forms of citrus scab—sour orange scab and sweet orange scab.  The former has been around east Texas as long as I can remember, but sweet orange scab has not been previously identified in Texas.

SOS affects the fruit of oranges, mandarins, their hybrids and lemons, while citrus scab affects sour orange, mandarins and their hybrids and lemons.  The latter is rare on sweet oranges.  Another major difference in the two diseases is that SOS is common on the fruit, but rarely appears on the leaves or twigs, while citrus scab is common on fruit, leaves and twigs.

APHIS has established a delimiting survey around the initial detection site (a backyard tree) and is presently going door-to-door to inspect for additional occurrences of the disease.


Professor & Extension Horticulturist
2401 East Highway 83
Weslaco TX 78596



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