AUGUST, 2009       

VOL. 23, NO. 8                                                                             





HLB in Mexico

As of June 26, Mexico has confirmed the existence of HLB “hot” psyllids in Tizimin, Yucatan, so it is likely just a matter of time until the disease is diagnosed in citrus trees in that area.  Tizimin is only about 180 miles north of the border between Quintana Roo and Belize, and the psyllid has been in Quintana Roo since at least mid-2007. 

This discovery is basically following the scenario that occurred in Belize, as HLB “hot” psyllids were discovered first, soon followed by the discovery of diseased trees.  There is little question that by the time psyllid samples in Yucatan were found to be carrying the disease, they had already been feeding on citrus or other hosts, thereby transmitting the disease.  Now, it’s a survey-survey-and-survey some more situation to find diseased trees.

Tizimin, Yucatan, is admittedly a long way from the Valley—across the Bay of Campeche, the crow flight distance is about 700 miles.  Overland, the distance is closer to 1100-1200 or so miles, crossing from Yucatan through Campeche to Tabasco, then through Vera Cruz to Tamaulipas.  In July of 2007, psyllids were reported in all of those states except Yucatan and Tabasco (now it’s in Yucatan, but I haven’t found out about Tabasco yet).  There are extensive citrus plantings in all of those states, as well as dooryard trees. 

The worst case scenario is that the bacterium will continue to spread from state to state along Mexico’s east coast until it reaches our border, as there is a practically unbroken line of citrus almost all the way.   Most of that area is below the Tropic of Cancer (which is just south of Ciudad Victoria).  In the tropics, the seasons are known more by the presence or absence of rain than by temperature or daylength, and citrus trees flush in tune with the rains.  Where the rainy season is long (which it usually is in the tropics), citrus may flush almost continuously for months, providing a nearly non-ending supply of new growth to attract psyllids.

While we in Texas have been rightly concerned about the potential movement of HLB from the east, now we have to also pay attention to what is happening to the south.  Hopefully, federal and state authorities and growers in the coastal states of Mexico will act to contain this threat before it becomes as widespread and destructive as it has in Florida.  Mexico has one potential advantage that Florida did not—the HLB bacterium is not already widespread in Mexico (presumably), giving them a reasonable shot at area-wide psyllid control, perhaps in the Yucatan Peninsula, to stop the western and northern movement of HLB.

This incident is somewhat reminiscent of the trek of the brown citrus aphid some years back.  In that case, almost everybody was expecting the aphid to reach the US (i.e., Texas) by way of Mexico, so we were pretty much all surprised when it island-hopped through the Caribbean to Florida.  With HLB, we have mostly focused toward the east (Louisiana and Florida), but now…?


Drought (noun).  1.  Period of dry weather—
a long period of extremely dry weather when there is not enough rain for the successful growing of crops or the replenishment of water supplies.  2.  Lack of something—a lengthy and serious lack of something (Encarta Dictionary).  Since there has been only about two inches of total rainfall in the last nine and a half months, both definitions of drought are applicable to our area.  It always used to rain in July—at least a little bit—but this July has come and gone with nary a trace. 

At least corn and sorghum growers have had good weather for harvest (assuming irrigated fields, though a lot are not), and irrigated cotton is already being defoliated and picked.  Preparation of fields for winter vegetables is well underway; cane and citrus irrigation continues unabated.

Still, the longer it goes without rain, the nearer the day when it will rain.
Given the lack of rain, what about the water supply in Falcon and Amistad?  Surprisingly, as of July 23, the conservation level of Amistad is 1117.00 feet elevation; the current level is 1116.88 feet elevation.  Total water is 3.268 million acre feet, of which 1.833 million acre feet is US water; the other 1.435 million acre feet belongs to Mexico.

At Falcon, normal conservation level is 301.20 feet elevation; the current elevation is 291.24 feet.  Total storage is 1.888 million acre feet, comprised of 1.163 million acre feet US water and 0.725 million acre feet Mexico water.

Given those data, stored water supplies in the two reservoirs are fairly close to normal conservation capacity—that is, Amistad is at conservation level, Falcon is down about 10 feet.  For those who didn’t know, the reservoir levels back on March 1, 2009, were at conservation level; consequently, a new five-year cycle of accounting for waters delivered from Mexico to the US began on that date.  Since that date, Mexico has delivered 89,044 acre feet of water against its annual requirement of 350,000 acre feet. 

TPA Meet

The Texas Produce Association Annual Convention is set for August 19-21 at the Omni Hotel in downtown Austin.   If you have decided to go but did not yet register, the good news is that the “early-bird” discount is being extended, so it is still in effect.
The registration flyer I saw does not show any “breakout” sessions for citrus or vegetables.  I don’t know if this is indeed the case or simply not the final program.

Other Meetings

The HLB/ACP task force is scheduled to meet on August 3 at 2:00 in the conference room of the TexaSweet Building in Mission.  The purpose is to review the proposed draft of our action plan, which Ray has sent out via email (it is more than 20 pages).
The Citrus Budwood Advisory Committee will meet on August 7 at 9:00 in the conference room of the Texas A&M University-Kingsville Citrus Center in Weslaco.  Various topics are on the agenda, including mandatory status for some varieties, tristeza update, et cetera.

Current Situation

The silver lining to the continued lack of rain has been suppressed pest population levels in groves.  Nonetheless, vigilance and preparation are still required as we move into August and September, since I cannot recall any year in the last 30 when drought conditions continued into those normally wetter months.  You can count on rust mites to really multiply once conditions become more favorable for their development.

Irrigation continues to be one of our major grove operations, but there is an ample supply of irrigation water for the time being.  The supply, however, should not be squandered, as who knows what rains the future could bring?

The heart of the hurricane season is upon us.  It has been barely a year since Hurricane Dolly, so that should still be fresh in our minds.


Professor & Extension Horticulturist
2401 East Highway 83
Weslaco TX 78596


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