Tomatoes in the News

• Gene discovery could lead to better tomatoesSan Francisco ChronicleThe discovery, made by an international research team headed by UC Davis, could have broad benefits to California's tomato industry - a $1.3 billion business. By looking at a collection of mutant and wild tomatoes at UC Davis collected in the 1950s by ...
• Tomatoes Ripe With Powerful Health BenefitsFood Product DesignResearchers from the National Center for Food Safety & Technology, Illinois Institute of Technology and ConAgra Foods Inc. examined current research to discover the role tomato products play in health and disease risk reduction. ...Tomatoes Pack A Nutritious Punch, Study FindsBETTER Health Researchall 3 news articles »
• Small Cancer Benefit Seen with Multivitamin UseMedPage TodayCo-authors disclosed relationships with the Tomato Products Wellness Council, Cambridge Theranostics, DSM Nutritional Products, BASF, Cognis, Pronova BioPharma, Pharmavite, Aurora Foundation, Bristol-Myers Squibb, AstraZeneca, Novartis, Merck, ...and more »
• Eat Your Heart Out With Healthy Red FoodsTyler Morning TelegraphProcessed tomatoes — sauce and paste — are more effective than raw tomatoes at reducing cancer risk. In the raw tomato, the lycopene is bound into the cell walls and fiber. Processing breaks down these cell walls and frees the lycopene to be absorbed ...and more »
• Counsel & Heal Tomatoes May Lower Risk of Stroke and Fight Prostate CancerCounsel & Heal(Photo : Flickr/PurpleFoodie) Experts say in the journal Neurology that cooked and/or processed tomatoes with cooking oil have the highest and most active levels of lycopene. Which makes sun-dried tomatoes the tastiest way to combat a stroke. According ...and more »
• Dan Morain: Will jobs be lost with cap and trade?Sacramento BeeRANDY PENCH / rpench@sacbee.com. Energy is needed to produce the steam that sanitizes gallon containers soon to be filled with processed tomatoes. Cap and trade costs at the plant remain to be determined. 7FO19FLUME.JPG ...

Process Tomato Blog

August 25, 2011

THRIPS/TSWV UPDATE

Our surveys in Fresno/Kings, Merced and Yolo/Colusa production areas have shown scattered presence of tomato spotted wilt virus (TSWV).  Although thrips counts are high, overall levels of TSWV remain low (<1-5% in most fields), but there are exceptions.  It is unlikely that TSWV infection now will cause economic loss in processing tomatoes, even with delayed harvest; late season fresh market fields are still vulnerable.

At this time in the season, management of TSWV depends largely on effective sanitation (destroying old harvested crops) and management of susceptible bridge crops, such as fall lettuce or radicchio. These crops are most vulnerable to infection if planted adjacent or nearby (e.g., less that ½ mile away) from plantings of pepper or tomato with known TSWV infections.  Also note that resistant tomato varieties do not show symptoms of TSWV infection, but may be infected with the virus.

THRIPS DENSITIES

Thrips population densities are very high (>1000 thrips/card and >5 thrips/flower collected every 2 weeks) in most fields in all of the surveyed locations the Fresno-Kings, Merced and Colusa-Yolo production areas. TSWV is now being detected in some thrips samples.

TSWV INCIDENCE

FRESNO-KINGS AREA:  With the exception of two fields, no monitored fields have or had more than 5% of plants with TSWV symptoms. In terms of the fields that currently have relatively high levels of symptomatic plants (>15%), which are located southwest of Mendota along I-5, there have not been increases in the level or distribution of the viral symptoms.  Although there was a field in northwestern Kings County with more than 7%, it was harvested in late-July. No TSWV has been detected in several monitored fields in the areas near San Joaquin and Firebaugh in Fresno County.

YOLO-COLUSA AREA: Thrips continue to be very high in all monitored fields, but TSWV has remained low (<1%) in most monitored fields. One exception is a monitored field in Sutter County, where TSWV incidence has reached 15% in some parts of the field.

MERCED:  Thrips population densities vary among monitored fields in Merced, but remain moderately high.  Levels of TSWV remain low in most monitored fields (<1-5%), although one field had levels of 15%.

AVOID PLANTING LETTUCE NEAR TOMATOES OR PEPPERS WITH TSW

Planting a susceptible crop, like lettuce, near TSWV-infected tomatoes (or peppers) should be avoided if possible.  Because processing tomatoes are likely to remain in the area longer than average, there is even higher risk for developing TSWV in lettuce. 

This can occur when large numbers of TSWV-carrying thrips move in the direction of prevailing winds at the time of the harvest of processing tomatoes.  Correct identification of the problem is the key in order to make the right decision for prevention or implementation of a solution (spraying for thrips).  A use of immunostrips (dip-stick tests) can provide on site confirmation of TSWV infection. 

Late season fresh market tomato fields will probably benefit from insecticide sprays to control thrips.  Recent test results from Tom Turini, UCCE Farm Advisor in Fresno County, has shown TSWV reduction with foliar applications of dimethoate, Radiant, Lannate, Beleaf, and Agrimek.  Be aware that insecticide tank mixes with fungicides to control powdery mildew may result in crop phytotoxicity, especially if a surfactant is also added to the mix.

FEEL FREE TO ASK QUESTIONS OR SEND US SAMPLES

As always, we encourage growers to contact us with any questions or for a field visit. We are particularly interested in confirming outbreaks of TSWV or other viruses in growers’ fields. This year, we are surveying more fields as part of an attempt to better determine the level of TSWV incidence that can result in yield loss and we are developing a thrips predictive model for thrips populations and a field risk index to provide growers more tools with which to fight thrips and TSWV.

Scott Stoddard

Farm Advisor

August 22, 2011

FIELD NOTES

Gene Miyao, Yolo & Solano County

Powdery mildew incidence is low to non-existent to date.

Fusarium wilt is much more prevalent and scattered about. Since many varieties have Fusarium wilt resistance to Race 1 and 2, we presume the disease is that of Race 3. Fusarium wilt race 3 resistant lines will become more valuable.

Late blight is reported as scattered in many areas of the region.          We’ve had coastal-like fog several weeks ago as well as many dewy mornings together with high humidity within fields. On August 22, we have another foggy morning around the Woodland area. If late blight was established in some fields that are several weeks away from harvest, continued preventive fungicidal sprays might be wise. Broad-spectrum fungicides would have greater utility to cover blackmold fruit rot as a preventive as well. Because of the delayed harvest of earlier plantings, we anticipate an overlap of fields ready to be harvested in September. While powdery mildew activity is low to nonexistent to date, that disease should remain a concern. Selecting fungicides such as Quadris Top® might be a part of that fungicidal program. Fields to be harvested in late September and beyond are at reduced risk of severe crop impact from mildew. At that late period, leaf drying won’t be as much of a concern because of generally mildew temperatures and shorter days.

Many ripening tomato fields in our area during mid to late August have major vine decline with loss of canopy. I’m working to identify some of the issues together with Extension Pathologist Mike Davis and others. We see many different diseases. Verticillium wilt severity is widespread as usual, but in some case, with greater severity. Fusarium wilt is increasing and should be noted to help guide management decisions in future years. Fusarium foot rot is also occurring. Russet mite damage is visible and expected over the years at various levels. It is not alarming as well as relatively easily controlled. Our bacterial speck from the late spring has clearly had a major impact in many fields.       There is more corky root rot in some fields as well. We’ve discovered another field planted to a nematode resistant variety with severe nematode damage in concentrated spots.

Overall, the level of leaf drying, vine collapse and sun-exposed fruit is high.       I am working toward a solution.              Within a field, it appears there are several factors involved.        Thus, identification remains a key to approaching economic remedies.

Late season vine decline may be a result of several contributing factors, such as Verticillium and potassium deficiency seen here.

July 26, 2011

FIELD NOTES

Gene Miyao, Yolo & Solano Counties

Our tomato crop is clearly behind our ‘normal’ harvest schedule. Heat units tracked this year from a Davis weather station indicate we are delayed. For a March 15 planting, the delay is about 15 days. The major set back period was mid May through mid June. The average heat unit accumulation per day during July, August and mid September is usually averages about 25 units.

Table 1. Heat unit measurements, 2011 vs historical average, Davis weather station

Our simple daily heat unit day calculation was: (Tempmax-Tempmin)/2 – 50°F).

Bacterial speck can also cause delays in days to harvest by suppressing plant growth and vigor as well as blighting flowers. For many fields, it appears flower set was substantially reduced. While a windshield assessment of many of these tomato fields would indicate plants had fully recovered, it is clear fruit set was greatly reduced while vine growth recovered to produce full sized plants.

On the positive side, with the milder temperatures, fruit set in fields without high disease is very good. We will have weak as well as very high yielding fields as the season progresses.

Tomato spotted wilt virus has become widespread in our area, but mostly at a low level (below 1%). The virus is vectored by thrips. Locally, thrips often remain at moderate to high levels from late spring to early fall. While the virus is a concern for all, it appears reasonable that geographic areas that have historical damage levels above 1% might include a spray program when plants are young and thrip activity is high. Perimeters of fields often are the most damaged, indicating an outside source of the virus. Within field spread from early infections and subsequent movement might well lead to high crop losses. Later infections, when plants are more mature, cause much less damage. Assess benefit of spray programs by leaving unsprayed check strips.            Alternatively, TSWV resistant varieties might be selected in future years, particularly in the historically highly impacted fields. However, the past incidence of TSWV isn’t always an accurate predictor of future activity.

March 30, 2011

Tomato Spotted Wilt Virus (TSWV) Update for Central California Processing Tomato Production Areas

Few TSWV-positive weeds detected

Tomato Spotted Wilt Virus (TSWV) testing of weeds has continued this month, with samples submitted from Tom Turini (Fresno County) and Michelle Le Strange (Tulare and Kings Counties).  Most of the weeds were free of symptoms, however, 1 out of 4 samples of Shepherd's Purse and 1 out of 42 samples of prickly lettuce were positive for TSWV by RT-PCR.  Both of these positive samples showed symptoms of slight mottling or necrotic spots on some leaves.  All the other weed samples (36 malva, 12 groundsel, 26 pineapple weed, 19 fiddleneck, 7 sowthistle, 5 bindweed and 41 prickly lettuce) were negative for TSWV.

Additional testing by Scott Stoddard (Merced County) of various winter-grown vegetables (radicchio, cabbage, arugula, beet greens, broccoli, red lettuce, and cardoon) found one sample positive for TSWV.

No TSWV-positive thrips emerged from test soils

In February we collected soil samples from areas that had heavy infestation of thrips and TSWV in fall crops. We are still not catching many thrips out of the soils, and the thrips emerged from these soils so far have not had TSWV.  In the soil samples that are being collected, there are volunteer tomatoes and many weeds.  To date, however, these volunteers and weeds, as well as the fava beans in the soil cages (used as indicator plants), have remained free of TSWV symptoms.

Weed control and sanitation is highly advisable

The results of previous and current weed and crop tests suggest TSWV overwinters in a relatively small number of some susceptible crops (e.g., lettuce and radicchio) and weeds.  Thus, in areas where overwintering TSWV has been confirmed, it is important that good field sanitation be practiced before planting tomatoes to limit the potential early spread of the disease.  Weeds and volunteer crop plants within fields and in adjacent fields should be thoroughly destroyed (by disking or herbicide sprays) prior to transplanting tomatoes.  Please contact your farm advisor if you suspect TSWV in recently planted tomatoes or in nearby crops and weeds.

Thrips levels

We have no information about how the recent wet weather will impact thrips (such as population growth and behavior), which would better enable us to predict relative levels of TSWV during 2011.  Cool, rainy weather is not favorable for thrips population increases -- yellow sticky card monitoring in numerous fields throughout the central valley has revealed very low thrips populations throughout the winter.  As of our last collection date, which was during the week of 14 March, thrips levels in Fresno County were zero to very low.  Additional monitoring sites will be placed in numerous fields throughout the central valley to continue our monitoring efforts.  Monitoring results will be posted every two weeks or more frequently if needed, through CTRI email, CTGA farm advisor blog, the Merced TSWV fax list, and others.

            Contacts for the UC TSWV Team:

            University of California Farm Advisors

     Brenna Aegerter - San Joaquin - 209-953-6114

     Gene Miyao - Solano/Yolo - 530-666-8732

     Michelle LeStrange - Kings/Tulare - 559-799-1250

     Scott Stoddard - Merced - 209-385-7403

     Tom Turini - Fresno - 559-375-3147 

     Joe Nunez, Kern - 661-868-6222

     Janet Caprile, Contra Costa - 925-646-6129

TSWV symptoms in weeds and other crops may be completely different from those in tomatoes (infected radicchio leaf shown).  Suspected virus infection should be confirmed with diagnostic testing.

March 28, 2011

Scott Stoddard, Farm Advisor, Merced & Madera Counties.  csstoddard@ucdavis.edu

Gene Miyao,  Farm Advisor, Yolo & Solano Counties.  emmiyao@ucdavis.edu

UC Cooperative Extension

Watch for Bacterial Speck

Recent weather has been conducive for the disease bacterial speck, caused by Pseudomonas syringae pv. tomato.  The disease is spread by splashing rain or sprinkler irrigation.  Physical injury to plant tissue from cultivation equipment, hail damage, workers, etc., increases crop susceptibility and disease severity

Symptoms typically are small dark specks on leaves often surrounded by a yellow halo.  The disease may be more pronounced at leaf margins and leaflet tips where moisture droplets collect.  As the pathogen spreads, individual spots expand to coalesce with other lesions and may blight entire leaflets.  In severe cases, large sections of petioles and stems may become infected and turn black.

Since plants are commonly treated with copper sprays in the greenhouse as a preventive measure, symptoms may not be detected at the time of delivery.  Nonetheless, additional preventative sprays may be needed in the field to keep this disease in check.  Before initiating a spray program, the following factors should be considered:

•  Weather forecast. Infected plants tend to recover once the weather turns hot and dry.
•  Recent history (last year) of speck in the field.  Speck overwinters in infected debris.
•  Diseased transplants detected from the greenhouse.
•  Ability to make application, especially with ground rigs. Thorough coverage is important,  as the copper spray program is only moderately effective. Ground rigs are the preferred  method.
• Grower’s tolerance to risk.  A reasonable approach may be to delay a spray program until after the disease is seen in the field.

March 12, 2011

Tomato Spotted Wilt Virus Update

Central California Processing Tomato Production Areas

 1. TSWV-infected weeds detected!

Controlling weeds now is critical for TSWV management in 2011 tomatoes.

TSWV has been detected in over-wintering weeds and crops in processing

tomato production areas in central California. In the Five Points area, sowthistle

plants collected from a vineyard tested positive for TSWV (4 TSWV-positive/10

sampled). The likelihood of early infection in tomatoes will decrease if the number

of TSWV-infected weeds in the area can be reduced. This will be especially

important as the temperatures increase and thrips become more mobile. If

infected weeds are suspected near tomato plants or other susceptible crops, use

a herbicide or disk to eliminate this important source of TSWV. This is

particularly important this season, as there were high levels of thrips and TSWV

infection in some tomato and lettuce fields in fall 2010.

 2. Spring lettuce: low thrips populations and no TSWV.

Ove rwinter thrips activity in spring lettuce fields in the Huron/Five Points areas in

Fresno County has been very low, as determined by yellow sticky cards collected

every 2 weeks (0 to 10 thrips per card). Consistent with this result, no TSWV-infected

lettuce has been found in this area.

 3. Winter radicchio: low thrips populations and a low TSWV incidence.

In Merced, thrips populations in winter radicchio fields were low, and low rates of

TSWV (less than 5%) were detected. However, in some harvested fields,

regrowth of disked radicchio plants has tested positive for TSWV.

 4. Regrowth of lettuce and radicchio plants after harvest can be a source of

thrips and/or TSWV for subsequent tomato crops.

As in the past, we have observed fields where regrowth of disked/plowed lettuce

or radicchio plants are infected with TSWV and harboring populations of thrips.

Thus, if field conditions allow, crop residues need to be disked and thoroughly

incorporated shortly after harvest to eliminate any potential for regrowth.

 Sowthistle plants with TSWV symptoms.

Your farm advisor should be contacted if you suspect TSWV.

     Contacts for the UC TSWV Team:

     University of California Advisors

          Brenna Aegerter - San Joaquin - 209-953-6114

          Gene Miyao - Solano/Yolo - 530-666-8732

          Michelle LeStrange - Kings/Tulare - 559-799-1250

          Scott Stoddard - Merced - 209-385-7403

          Tom Turini - Fresno - 559-375-3147