In This Issue
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Vegetable Culture Meeting for Starr County
A meeting featuring topics on crop fertility, vegetable physiology and pesticide safety will be offered on Thursday February 12 beginning at 10:00 am at the El Comal restaurant on business 83 in Rio Grande City. The program will feature Bob Wiedenfeld and Lynn Brandenberger with Texas A&M and will qualify participants for a 1 hour CEU credit toward their TDA pesticide applicator's license. For more information regarding this meeting, contact Mr. Enrique Perez, Starr County Agricultural Extension Agent at (956) 487-2306.
Watermelon Meeting in Falfurrias
Watermelons and other vegetable crops grown in the Brooks, Jim Wells, Jim Hogg and Duval County area will be the focus of a meeting sponsored by the Texas Agricultural Extension Service on Wednesday February 18. The meeting will run from 9:00 am until 12:00 noon at Mr. Robert's Restaurant on South 281 in Falfurrias with lunch sponsored by the National Watermelon Promotion Board. The program will feature William Watson of the National Watermelon Promotion Board, Tom Isakeit, Juan Anciso, Jason Johnson and Lynn Brandenberger of the Texas Agricultural Extension Service. This program will offer 3 CEU's toward your private applicator license registration maintenance. For more information regarding the program contact Mr. Jaime Lopez, Brooks County Agricultural Extension Agent at (512) 325-4402.
27th National Plastics Congress Feb 18-21, 1998
The congress will be held in Tucson, Arizona on February 18-21, 1998. The 27th Congress is dedicated to integrating new technologies from both scientists and farmers. It is this cutting-edge information that will chart the course of food and fiber production into the next century. Nearly 80 presentations are scheduled, along with tours that will showcase; controlled environmental agriculture, integrated plant and fish systems, drip irrigation, chemigation, mulches and row tunnels. In addition, there will be a post-conference tour to Mexico. For more information contact American Society for Plasticulture at: 526 Brittany Drive, State College, PA 16803, or call Dr. Merle Jensen, Congress Chair University of Arizona at (520) 621-5242, e-mail at: mjensen@ag.arizona.edu.
Small Acreage Crops of Texas
A report by Dudley Smith TAES scientist with the department of Soil and Crop Sciences outlines in concise form information on 100 different crops grown in Texas. The report titled: "The Small Acreage Crops of Texas: an Inventory and Assessment Departmental Technical Report 98-02" gathered facts and estimates from over 40 recognized experts regarding these crops. The report gives a background for this crop grouping, crop statistics, EPA and IR-4 crop groupings, production regions and specific statistical and background information on 85 horticultural crops and 15 agronomic crops. This information should
really help in filling the information void that has long been associated with small acreage crops.
If you would like to receive a copy of the report contact Dudley Smith at: Department of Soil & Crop Sciences, College Station, TX 77843-2474, or contact Lynn Brandenberger at: Texas A&M Research and Extension Center, 2401 E. Hiway 83, Weslaco, TX 78596.
Diseases Affecting Watermelon Fruit in South Texas by Tom Isakeit
The unfortunate thing about finding disease symptoms on fruit is that identification of the problem can not lead to action that will provide a solution. It is too late. In the case of bacterial fruit blotch, at least knowing the cause can give growers the option to prevent future problems. But usually, with many soilborne diseases, there is no expectation that fruit diseases can prevented in the future. However, the appearance of many of these diseases is dependent upon favorable (usually extreme) weather or growing conditions. There may also be an interaction between these weather conditions and the cultivar. So, a problem seen in one year may not be seen again.
Bacterial fruit blotch: The fruit symptoms start as water-soaked spots that enlarge over time, but remain firm. The lesion has a dark, oily appearance and may have cracks with a brown gummy exudate. The infection does not cause decay of the fruit, but the cracking of the rind can allow entry of secondary pathogens that can cause fruit rot. Lesions are usually found in the light portions of striped fruit and light fruit is more susceptible to this disease than dark fruit. The disease may appear to develop overnight, but actually, the pathogen was present all along on the foliage of plants. Mature fruit will not become infected, so the disease will not spread to other watermelons in storage. If this disease is present in a field, control measures need to be taken to ensure that it does not become established. These measures include at least a two year rotation away from watermelons and other cucurbits, as well as a vigorous control of volunteer watermelons and any cucurbit weeds in the field during this time.
Bacterial rind necrosis: There are no external symptoms of this disease. When the rind is cut open, brown areas are seen in the rind. These areas are not rotted. The flesh is rarely affected. The circumstances leading to the disease are not clear. Something triggers the growth of low populations of bacterial that are naturally present in the rind, leading to the necrosis. This can be a combination of cultivar and growing conditions. The incidence of this problem can be very low in a field, but because affected fruits can not be culled, the crop from a field may become unmarketable. There are no control recommendations, although a grower should investigate whether other cultivars are also affected in the same field.
Belly rot: This disease can be caused by several species of soilborne fungi. One symptom is the appearance of a small, water-soaked spots that enlarge and become soft. Often, a white fungal growth can be seen on the outside of the fruit or even on the inside, where the fruit is decayed. Fruits infected with Pythium aphanidermatum are soft and have a dull brown appearance. Another species, Sclerotium rolfsii, the southern blight fungus, produces a profuse, white growth on fruit, and later, small, tan spherical survival structures that resemble mustard seeds. Belly rot becomes a problem when soil remains saturated for a prolonged period of time, particularly when temperatures are high. If soil drainage problems can not be alleviated, then plants should be grown on raised beds, particularly on plastic mulch.
Pimples: The symptoms are small bumps or pimples on fruit. There may also be ringspots (circles of darker coloration) or raised, brown, concentric rings. These symptoms can be caused by the tobacco ringspot virus. This virus is vectored by the dagger nematode. Other species of nematodes, such as the root knot nematode, do not vector this virus. (The presence of the dagger nematode in a field can not be determined by visual symptoms, but only by a soil test). High populations of this nematode have been found in weedy fields or in pasture land. Thus, this problem may occur on new watermelon land. The epidemiology of this virus on watermelons has not been studied. In South Carolina, the virus was found in smooth pigweed growing in a squash field and was found to be seed-transmitted in this weed. Back in the 1950's, this virus was documented on many weeds and crop plants in the Lower Rio Grande Valley. This virus has a similar appearance to the early symptoms of anthracnose, a fungal disease. (However, anthracnose has NOT been documented in south Texas; apparently, the climate is not favorable for this disease). With pimples disease, the pimples do not change in size and the fruit remains firm. With anthracnose, the pimples become concave, enlarge, and eventually affect the flesh, leading to fruit decay.
The control for tobacco ringspot virus is to aggressively control the weed hosts that harbor the virus. Cultivation and fallowing of land will lead to a decline of populations of the dagger nematode, so a nematicide treatment may NOT be necessary, or even make a difference. If in doubt about the presence of economically-damaging levels of this nematode, soil should be tested.
Physiological disorders: These physiological disorders are not common, particularly in fields that are properly maintained and have not been subjected to extreme weather conditions.
Blossom-end rot is caused by a calcium deficiency in the fruit and occurs in plants subjected to drought stress. The initial symptoms are brown spots at the blossom end of the fruit which later enlarge, darken and become leathery. Decay may occur as a result of microbial activity. Cultivars can differ in their susceptibility to the problem. Watering operations that avoid drought stress can reduce or eliminate the problem. Excess nitrogen fertilizer may also contribute to blossom-end rot.
Bottle neck or otherwise misshapen fruit can be caused by pollination problems or fluctuations in watering. Cultivars can differ in susceptibility.
Cracks scarring, and pitting can be caused by mechanical damage when fruits are young, Insects can also cause such injury.
Splitting is caused by an erratic watering pattern, particularly the excessive accumulation of water. The inside of the fruit is under great pressure and the fruit splits open when lightly tapped. Never, ever refer to this as "exploding", as this term is not an accurate or market-friendly description of the problem. This condition is weather related and there probably is a cultivar interaction as well.
Food Quality Protection Workshop by Stormy Sparks
It looks like some progress may be made in implementing the Food Quality Protection Act (FQPA). A workshop on FQPA will be held in St. Louis on February 18-19 to provide details on how it will finally be implemented. Sessions are also scheduled to provide feedback and discussion on the potential impact of FQPA on all aspects of agriculture.
FQPA was originally a much anticipated change from the Delaney Clause, but as details are revealed, it appears that agriculture may have jumped from the frying pan into the fire. Hopefully, in a rather short time, we will get answers to many of the questions that have been asked since the passage of FQPA. Only then will we know what we are facing and how we can best proceed to continue to be productive and simultaneously address the health and environmental concerns the general public expresses toward agriculture.
Fall Southern Pea Trial Results J. Lopez, R. Mercado, L. Brandenberger
Southern pea production in South Texas has consisted primarily of fall production of "eyed" types for the processing market. In 1996, a fall variety trial was completed near Falfurrias, Texas with nine different southern pea cultivars including several that normally require shorter growing seasons, having bush type growth habits and erect pod setting. During the fall of 1997 this trial was expanded to twenty four different cultivars including nine from the previous year and additional
advanced breeding lines from a university breeding program.
All cultivars were direct seeded September 10, 1997 near Premont, Texas in a randomized block design with four replications. Plots were one row wide by 25 feet long with a 30 inch spacing between rows and an in-row plant spacing of approximately two inches. The trial was grown in a commercial field that received no supplemental irrigation and received five gallons of 4-29-2 fertilizer per acre as a preplant application. Weed control utilized both Prowl herbicide applied at a rate of one quart per acre prior to planting and cultivation.
This trial provided an opportunity to observe several southern pea cultivars under less than ideal conditions. The cool and cloudy weather experienced during the trial was in contrast to the warm and sunny weather normally required by this crop for proper growth and development. Because of this, cultivars included in the trial were seriously slowed in their flowering (Table 1), and pods were very slow to develop and mature. In the past, several of the cultivars included in this trial have gone from being planted to fully mature and dry peas in 55 to 60 days; this contrasts with the nearly 100 days required to complete this trial. Although yields in the trial were considerably lower than expected, several cultivars in the trial produced 400 or more pounds of peas per acre compared to many commercial fields that were not harvested. Future trials will hopefully operate under better conditions and will allow producers in the area an opportunity to observe these cultivars under conditions better suited for maximizing their performance.
We would like to acknowledge Mr. John Prukop of Los Machos Farms for providing an area for the trial and for his time and efforts to make this project successful; and Mr. Lloyd Grace of Allen Canning for his assistance and advice. We would also like to thank Mr. Carl Smith, Holley Linkenhoger and Dr. T.E. Morelock for supplying seed for the trial.
For a complete and detailed report on the trial contact either Jaime Lopez/Brooks County Agricultural Agent at (512) 325-4402 or Rogelio Mercado/Jim Wells County Agricultural Agent at (512) 668-5705.
| Table 1. Fall 1997 southern pea trial, Premont, Texas, maturity rating, net yield, percent moisture, percent increase in wieght from soaking. | ||||||
| Cultivars | Maturity rating on 10/05/97 (z) | Net yield lbs./acre 12/18/97 | % moisture of peas at harvest | % increase in weight from soaking | ||
| Early Scarlet | 2.4 | bcde | 522.8 | a | 18.6 | 129.5 |
| Excel | 2.9 | abcd | 344.2 | bcd | 17.9 | 135.2 |
| Arkansas 87-435-68 | 2.4 | bcde | 310.9 | bcde | 17.9 | 144.5 |
| Arkansas 92-551 | 0.6 | ij | 48.4 | gh | NA | 57.4 |
| Arkansas 92-552 | 0.9 | ghij | 105.6 | fgh | NA | 53.4 |
| Arkansas 91-285 | 2.4 | bcde | 402.2 | ab | 15.8 | 100.9 |
| Arkansas 95-195 | 1.8 | efg | 271.6 | bcdef | 13.5 | 98.3 |
| Arkansas 95-241 | 2.1 | cdef | 248.3 | bcdef | 12.9 | 133.4 |
| Arkansas 95-242 | 3.0 | abc | 256.7 | bcdef | 12.9 | 125.6 |
| Arkansas 95-273 | 0.8 | hij | 63.9 | gh | NA | 39.8 |
| Arkansas 95-274 | 0.4 | j | 129.4 | fgh | NA | 34.2 |
| Arkansas 95-301 | 3.3 | ab | 213.1 | cdefg | 12.9 | 129.1 |
| Arkansas 95-368 | 3.5 | a | 400.5 | ab | 12.8 | 120.0 |
| Arkansas 96-556 | 3.5 | a | 197.6 | defg | 13.5 | 135.8 |
| Arkansas 95-671 | 3.0 | abc | 171.7 | efgh | 13.9 | 131.4 |
| Arkansas 96-593 | 3.8 | a | 323.1 | bcde | 13.7 | 139.1 |
| Arkansas 96-868 | 2.4 | bcde | 374.8 | abc | 20.5 | 120.6 |
| Arkansas Blackeye #1 | 2.1 | cdef | 401.2 | ab | NA | 105.2 |
| Arkansas 95-104 | 1.6 | efgh | 64.0 | gh | 15.0 | 122.2 |
| Arkansas 95-105 | 1.1 | fghij | 55.9 | gh | 14.7 | 125.8 |
| Pink Eye Purple Hull BVR | 1.9 | def | 104.6 | fgh | 14.3 | 115.3 |
| Coronet | 1.4 | efghi | 164.2 | efgh | 16.3 | 98.9 |
| Quick Pik | 3.0 | abc | 121.6 | fgh | 20.1 | 120.5 |
| Texas Pinkeye | 2.1 | cdef | 23.8 | h | 12.9 | 157.8 |
| (z) Numbers within a column followed by the same letter are not statistically different where P=0.05. | ||||||
Lynn Brandenberger/Editor
The information given herein is for educational purposes only. References to commercial products or trade names are made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.