SEPTEMBER, 2010      

VOL. 24, NO. 9                                                                             

IN THIS ISSUE:

EARLY FLORIDA ORANGE ESTIMATES
WATER RECEDING
LOSING TEMIK
SWEET ORANGE SCAB
ORIENTAL FRUIT FLIES IN FLORIDA
CURRENT SITUATION
FLOODING AND CITRUS

EARLY FLORIDA ORANGE ESTIMATES

Both Elizabeth Steger and Louis Dreyfus Inc have released their estimates of the upcoming Florida orange crop.  Steger pegs the crop at 154 million boxes, which is up about 15 percent from last season’s final.  Dreyfus comes in a little lower at 149 million boxes. The USDA and Florida Ag Statistic Service estimates will be released in early October.

WATER RECEDING

The International Boundary and Water Commission stopped releasing water from the river into the Valley’s floodways during the third week in August.  Releases from Falcon Dam had been reduced substantially, even though above average inflows are still being recorded at Falcon, but storage elevation has dropped to just below conservation level.  Meanwhile, the Floodway has receded to its normal status at the Expressway in Mercedes as of August 23. 

Most of the flooded crossings of the Floodway and the Arroyo Colorado have been reopened as TXDOT has checked the  bridges and low-water roadways and opened them for vehicular traffic.

LOSING TEMIK

EPA and Bayer Crop Science have agreed to eliminate the use of Temik on citrus (and potatoes) entirely and phase out its use on all crops within a few years.  According to official news releases, citrus growers can continue to use up existing supplies of Temik through December, 2011.

That news is especially sad for Texas citrus growers who have relied on Temik to control nematodes, mites and a few other pests, including Asian citrus psyllid.  Given the industry efforts to suppress/control psyllid and the northward movement of citrus greening from the Yucatan around the Bay of Campeche, the loss of Temik will impact our psyllid suppression efforts in the winter and spring months.

SWEET ORANGE SCAB

As reported last month, sweet orange scab (SOS) was confirmed on lemon and tangerine trees at a residential property in Harris County.  The detection occurred during the annual commodity survey by Texas A&M under the Citrus Health Response Program (CHRP).  Six additional detections of SOS were located on four residential properties near the initial detections. 

In addition, SOS was detected on satsumas at a small farm in Orange County.  Then, on August 20, APHIS-PPQ confirmed SOS on a single tree in Orleans Parish, Louisiana.

Presently, USDA-APHIS-PPQ, Texas Department of Agriculture, Texas A&M University, LSU, and the Louisiana Department of Agriculture and Forestry are coordinating efforts to determine the source of this disease and its extent in the two states.  As you should know, these are the first known reports of SOS in the US.

ORIENTAL FRUIT FLIES IN FLORIDA

The Florida Department of Agriculture has just announced that two male oriental fruit flies were trapped in a grapefruit tree in Pinellas County.  As a consequence, trapping is being intensified in an 81 square mile area around the original detection.

CURRENT SITUATION

Most of the problems that irrigation districts were facing in regards to delivery of irrigation water to farmers have been resolved.  As you might suspect, some pumps had to be removed from the river or disabled at the time of the flooding, but I have been told that growers who were experiencing delays in getting irrigation water have now been able to water.  Ironically, despite the flooding, rainfall during July and August has been rather sparse and the need for irrigation has intensified.

Fruit is sizing nicely, and packinghouses have been making in-house estimates of tonnage for the current season.  As the month progresses, they will commence sampling for maturity tests so as to start picking as soon as possible.

There is nothing new being reported about the progress of citrus greening in Mexico,   As the saying goes, no news could be good news.

Meanwhile, perhaps the Sirius days of summer will begin to give way to a little cooler weather in the coming days.

FLOODING AND CITRUS

The standard mantra in citrus circles is that citrus on sour orange rootstock will begin to die after three days of flooding.  Nonetheless, we have seen conditions following heavy rains in which groves were inundated for four to six days without ill effects. 

The recent flooding is giving us some new insights into how citrus trees fare after several weeks of being underwater.  Young trees (three or four years old) were killed under three to four feet of water.  These trees had only about a fourth of their canopy above water and there was nothing green visible.  When the water receded after about four weeks, it was obvious that the trees were entirely dead—the bark on the trunks was  peeling off down to the ground.

Older trees were unfortunately subjected to about a month of being from about one to four or five feet under water.  Surprisingly, those that were only under a foot of water seem to be intact.  Conversely, those under the most water (and therefore the longest time) are showing significant dieback scattered throughout.  All limbs, leaves, twigs and fruit that were underwater are dead, with bark sloughing off the twigs and limbs, and in some cases parts of the trunk.  The waterline is quite obvious, as there is a distinct absence of green below the high water mark. 

In comparison, younger resets in some of the older blocks are dead—just as the solid planted younger orchard.  Bear in mind that this was not stagnant water, i.e., the water was flowing through most of the grove as it is in the river’s floodplain.  So, why did the younger ones die?  I suspect that the younger trees with their smaller root systems simply could not obtain sufficient oxygen to sustain them. Too, it is possible that their bark is more susceptible to Phytophthora because of their more rapid growth.  

Nonetheless, it seems that the dieback is probably the result of Phytophthora infections—both on the roots as well as on the smaller branches and the trunks. The future of these trees is uncertain at the moment, as no one believes that the dieback is over.  An application of Alliette to the trunks followed possibly by a foliar application of phosphonic acid may help overcome the Phytophthora.

I am continuing to follow the progress of this orchard, not only because there is more to be learned there, but also because it belongs to a friend of mine.

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