SPRING
CROP MOVEMENT
SAPOTE FRUIT FLY QUARANTINE
THE QUARANTINE AND WINTER TEXANS
VINE CONTROL PROJECT
CURRENT SITUATION

SPRING-

Ole Man Winter just doesn't want to go quietly into the past, as evidenced by the very cold temperatures that we are experiencing in the last week of February-from shirt sleeve, normal weather to the 30's and 40's takes a little getting used to! The Texas mountain laurels are blooming, but they can be fooled; Spanish daggers, however, are never fooled (according to local folklore) and they are blooming, too. Well, perhaps they weren't fooled, as the story goes that no freezing temperatures will occur after the Spanish daggers begin to flower-and it wasn't freezing, just close to it.

Normally, navel oranges would be in peak bloom by now, but they are just starting to push out. Generally, even round oranges would be beginning to flower at this time of year. The generally cooler weather of this winter has set up a very good flower induction and it has delayed the onset of the spring flush by a week or so. The delay could be longer, inasmuch as colder than normal temperatures are being predicted into the first week of March.

At the least, it would be helpful for the mist-drizzle of the last several days to give way to full-fledged rains to bring soil moisture levels to field capacity before the peak of the flush begins.

CROP MOVEMENT-

Fresh citrus sales are still in the pits, with total crop movement through mid-February being only 84.0 percent of last season. Navel volume shipped fresh amounts to only 70.3 percent of last season, while early and mid's are at 76.2 percent. Grapefruit is somewhat better at 88.3 percent of last season's volume.

Neither the reduced movement nor the generally lower f.o.b. prices make a whole lot of sense. Normally, a short crop season is reflected by generally higher f.o.b. prices, but not this season. Too, a short crop would normally move out at about the same pace year-to-year, but not this season. In other words, we have a reduced crop which is being marketed at a reduced pace and which is bringing lower f.o.b. prices.

True, Texas citrus is not in control of the fresh market-but Florida's grapefruit and orange crops are both down substantially from last season. California's orange crop is up somewhat, though not enough to offset the overall U.S. orange crop reduction-California's oranges are grown for the fresh market.

SAPOTE FRUIT FLY QUARANTINE-

Anastrepha serpentina, commonly known as the sapote fruit fly, has been trapped in roughly two locations in the Valley since January a male and 2 immature females in south McAllen and 2 immature females north of Donna. Because of the proximity of the finds in each area, quarantine protocols have been implemented by TDA. The overall area under quarantine is about 225 square miles, forming a lazy 8 configuration encompassing the centers of the two finds. Generally, the zone extends west to east from east Mission to Highway 1015 in Weslaco, and north to south from Hidalgo to just below Edinburg on the west area, and from just south of Donna to just across Highway 107 in the eastern area.

With an estimated 5,000 acres of citrus in the quarantine area, this is a serious event. No one seems to know how much unharvested fruit remains in the area. What does it mean to the citrus grower? More bad news to go with a season that just has not been all that great to begin with.

It is my understanding that no fruit may be harvested for fresh use from trees within roughly a half mile of any one of the 5 finds (the so-called core area) this fruit can only be harvested direct to the juice plant, and even then, the transport of such fruit to the plant must be directed by USDA-APHIS.

Fruit outside the core areas but within the quarantine zone may be harvested for fresh market shipment under one of two conditions-the fruit is subjected to methyl bromide fumigation after packing but before shipment or the groves are treated with bait sprays. Most packinghouses have the capability to fumigate the fruit. I do not know the protocol for the bait spray treatments, though I am confident that such information has already been provided to growers.

Although no larva has yet been detected, one should expect this quarantine to last the rest of the season, as protocols require the absence of new finds for 3 life cycles of the insect. Given the cool weather to date this season, it is unlikely that the 3 life cycles will occur before the season ends.

What is a sapote? Actually, there are several-all of which are tropical fruits. The black sapote is related to persimmons, both green and mamey sapote are Calocarpums, while the white sapote is Casimiroa, a more cold-hardy genus which has occasionally been grown in the Valley. There is also a yellow sapote in another genus. Mamey is the most commonly known sapote-but even it would not be recognized by most people outside the tropics. However, it is probably irrelevant that the fly is called "sapote fruit fly"; that is probably the fruit on which it was first detected and identified many years ago. Most fruit flies can infest a large number of different kinds of fruits, as you well know.

THE QUARANTINE AND WINTER TEXANS-

As you know, a lot of Winter Texans are heading home every day and many of them take quite a bit of fruit with them, both that which they grow and that which they buy from fruit stands. Since the announcement of the quarantine, Extension offices and everyone else is being besieged with queries as to whether or not they can take fruit back with them. This shows that these folks are sensitive to the problems that such fruit flies can cause, which is to be commended.

To the best of my understanding, no fruit can be taken from the core areas of the quarantine, period. Moreover, fruit from the rest of the core area cannot be moved unless it will be fumigated or the trees/grove will be bait-sprayed, neither of which is likely for either home-grown nor fruit stand citrus.

Consequently, Winter Texans and other tourists in the quarantine area would be well-advised to either A) buy the fruit from a packinghouse (so it is either bait sprayed, fumigated or grown outside the quarantine area) or B) buy their fruit from fruit stands or orchards outside the quarantine area.

Many within the quarantine area will undoubtedly take fruit from their own trees, regardless. However, not much is known about the survivability of this fruit fly in temperate climates where most of those folks are headed; but the host range of fruiting plants is quite varied, so I would not want to take the chance of possibly introducing this pest to other areas which might have susceptible fruits and vegetables.

VINE CONTROL PROJECT-

This effort, which is being partly funded by the Texas Citrus Producers Board, is still underway. The weather has not, as you know, been terribly amenable to extensive field work recently. We were hopeful that the use of 2,4-D in controlled, directed sprays, might be an approach that would receive company support for local needs labeling?but that is not the case, at least from what I have heard. Nonetheless, I still intend to test it on possum grape, since that is such an onerous vine to control. Too, there are other 2,4-D products on the market, so we'll see.

Regarding milkweed vine, which appears to be the one of most concern to growers, there used to be a biological material called DeVine made by Abbott Laboratories that was completely effective. Essentially, DeVine is a cultured Phytophthora fungus that was first identified on dying milkweed vines in Central Florida groves over 20 years ago. The species of Phytophthora is highly host specific to milkweed vine.

I am told that DeVine is still available, made by another company but I have not yet determined who or if. I will say that I tested this product in a local grove back in the early 80's with complete eradication of milkweed vine from the test grove. The formulation in those days did not lend itself well to flood irrigation, but I managed to disperse it into the flood stream by diluting it substantially, then going from valve to valve (several times during the irrigation), dribbling about a cupful at each valve each time.

Dispersion through a drip or microsprayer system seems feasible-the diluted material would have to be dispensed into the intake stream for a certain minimum amount of time. The filters will remove the substrate on which the fungus is cultured, leaving the spores to pass on through the filter and into the emitters.

If anyone knows whether or not the product is still available and who makes it, send me an e-mail (j-sauls@tamu.edu)so that I can pursue this. As I recall, it had to be special ordered along about May for use in early summer.

CURRENT SITUATION-

With the weather having taken a turn to the nasty side, grove operations have pretty much stalled for the time being. Harvesting is still proceeding, and projections are for an earlier end-of-season than we have seen in the last few years.

With the spring flush and bloom just around the corner, most grove operations should be about caught up in any case with the possible exception of herbicide applications. The next major endeavors will be post-bloom pest control, mostly citrus rust mite, and necessary irrigation.

As you already know, the current supply of water will not carry us through this season, so hope for additions to the supply (especially from rainfall, as it is unlikely to come from debt repayment!) and timely rains during the season.

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