APRIL, 2010      

VOL. 24, NO. 4                                                                             

IN THIS ISSUE:

MORE GREENING IN MEXICO
CG--RESIDENTIAL SURVEY RESULTS
CG--APHIS-PPW SITC RESULTS
OTHER CG NOTESINTERCEPTIONS IN NORTH DAKOTA
CROP UTILIZATION
BLOOM SITUATION
CURRENT SITUATION

More Greening in Mexico

Mexico continues to document new finds of citrus greening in the four states where it has previously been reported, and they have now reported the disease in trees in the state of Campeche.  The good news, if you care to call it that, is that the Campeche finds are far down in the SE corner of that state.

The overall totals for Mexico as of March 17, 2010, include 96 positive tests of the psyllid, with over half of those being from Nayarit on the Pacific coast.  Tree detections total 480, broken down as 102, 164, and 15 from the eastern states of Quintana Roo, Yucatan and Campeche, respectively, with 13 and 186 from the western states of Jalisco and Nayarit, respectively.

CG—Residential Survey Results

Through March 29, the residential surveys in the Valley by USDA-APHIS have collected 17,553 plant samples, of which 4,530 were selected after screening to be subjected to PCR analysis.  During the same time frame, 21,516 psyllid samples have been collected and forwarded for PCR analysis.

Fruit fly trappers have collected 1070 tissue samples, of which 23 survived screening at USDA-APHIS and were forwarded for PCR analysis.  In addition, growers have submitted 425 tissue samples for PCR analysis. 

All samples to date—both tissue and psyllids—have been found to be negative for the bacterium.

CG--APHIS-PPQ SITC Results

APHIS-PPQ SITC (Smuggling Interdiction and Trade Compliance) have had a busy fiscal year, with some 139 citrus-related market surveys (in Texas) and another nine surveys of e-commerce.  The former included 17 seizures (and destruction) of citrus or citrus-related articles.  In the Dallas area, seizures included kaffir lime leaves, Satsuma and tangerine fruit, 14 kumquat trees and 124 citrus trees.  All were traced back to quarantine areas in California, excepting one kaffir lime seizure that came in from Thailand via Canada.

In the Houston area, four seizures included tangerine fruit with stem and leaf tissues, lime leaves and dried curry leaves.  Closer to home, there was one seizure of kaffir lime leaves in the Pharr sector, originally from Thailand via Canada.

In the market of e-commerce, the following citrus-related seizures were sold on E-Bay:  a kumquat tree and a satsuma tree, both from Georgia, were seized in separate events in the Los Indios sector.  In Pharr, key lime seeds from Malaysia were seized.  In Houston, one batch of kaffir lime seeds from Thailand were confiscated.  Finally, in Dallas, kumquat seeds from Georgia, key lime seeds from Malaysia and lemon seeds from Malaysia were also seized.

The APHIS-PPQ SITC reports are frightening enough regarding the interceptions of seeds, leaves and fruit of citrus, but there were 138 citrus trees from California intercepted in Dallas, while there were two citrus trees from Georgia intercepted in the Los Indios area.  In case your geography is a bit rusty, Georgia abuts Florida (where citrus greening is widespread) and Georgia has itself been quarantined for citrus greening for nearly a year.

As Pogo stated in a comic strip some 40 years ago, “we have met the enemy and he is us”. 

Other CG Notes

I have not yet gotten in contact with Customs and Border Protection to be able to report their citrus-related operations, but I am working on it.  The same is true for Texas Department of Agriculture, though I believe they are scheduled to conduct a joint effort with SITC during April.

APHIS is currently planning a greening survey effort in Valley citrus groves similar to what is being done in dooryards, but the final details are not public as yet.

Crop Utilization

Through mid-March, the Texas Valley Citrus Committee weekly utilization reports indicate that overall fresh shipments of grapefruit are down about 3.7 percent from last season to date, while processed grapefruit utilization is down 21.0 percent for the season.

Early orange shipments, excluding navels, are about even with last season, while navel shipments were up 23.6 percent over last season.  Processed utilization of early oranges and navels is down about 4.4 percent. 

Valencia fresh shipments are down about 5.4 percent, while processed Valencias are down a whopping 63.2 percent. 

Bloom Situation

This season’s bloom was late, primarily because of cool weather that persisted into March.  Navels didn’t really peak until early March, oranges a little later and grapefruit seems to be all over the place—some groves have peaked, others haven’t.  The bloom was heavy, for the most part, again owing in part to the persistent cool weather that a) induced a goodly number of flower buds but b) was also too cool to allow those buds to be initiated early. 

As you might recall, many prior winters have brought cold fronts followed by a few days of quite warm weather, then another cold front.  The intermittent warm-ups usually result in several cycles of flower bud induction and initiation, which sometimes is manifest with multiple blooms.

Current Situation

Temperatures have not yet warmed up into what might be considered normal—I think the only time that the thermometer broke 90 in the mid-Valley was on Good Friday.  Rainfall patterns have reverted to normal, meaning none, since about mid-February.

With the development of young fruit, you can expect to see citrus rust mites move from the twigs and young leaves onto the developing fruit.  If you check the new flush, you might have trouble finding much in the way of psyllids—though if you look closely, you may notice the “notched” leaf tips that indicate that adult feeding did occur earlier.  Hopefully, grower efforts to control overwintering adults before the flush are having an impact.

In that regard, Danitol now has a low-volume label, and there are a few of the LV-8 low volume applicators around.  These rigs are designed to put out only about 5 gallons of spray per acre at a ground speed of up to 7 mph.  The caveat is that because of the very fine droplet size and our more or less normal strong winds, the ideal time for application will be late at night when the winds are the calmest.  Presently, the recommendation is to spray for psyllid just before the growth flush, the next one of which should be coming up sometime in May.

In Florida where citrus greening is so widespread, many growers are using LV equipment (or aerial in many cases) in more or less monthly applications, often in alternate middles, to try to contain the spread of greening by stringent control of the vector.  While Texas growers are not necessarily going to accept that kind of vector control effort at the present time, it makes good sense to incorporate something for psyllid control in the mite/scale control program throughout the season. 



JULIAN W. SAULS, Ph.D.
Professor & Extension Horticulturist
2401 East Highway 83
Weslaco TX 78596