Cover Crops Provide Many Benefits-But Must be Terminated


Cover crops are crops that are planted between the traditional growing seasons and generally without intent to harvest. Cover crops provide many benefits: reduced erosion, reduced nutrient leaching, increased soil organic matter, and improved soil productivity. However, cover crops need to be terminated so that the next crop can be planted and herbicides are a preferred termination method, as described in a recent article about a progressive California tomato farmer……

“During the past seven years, Sano Farms… has also refined a production system for processing tomatoes that uses cover crops, subsurface drip irrigation, and conservation tillage practices. Their system saved fuel by reducing the number of tractor operations, cut fertilizer inputs, reduced labor, improved soil condition, reduced overall variation in yield, and increased tomato yields up to 15% relative to the standard practices that were previously used.

An important component of the integrated tomato production system at this farm is the use of winter-grown triticale cover crop. These cover crops are typically seeded in late October or early November, sprinkler irrigated as part of the farm’s “preirrigation” program for the subsequent year’s crop, and then ended with herbicide typically in early February before the aboveground growth becomes too difficult to manage.”

Authors: Mitchell, J. P., et al.
Affiliations: Department of Plant Sciences, University of California..
Title: Evolution of conservation tillage systems for processing tomato in California’s central valley
Source: Hort Technology. October 2012. 22(5):617-626.

The Dilemma of Insect Fragments in Processed Tomatoes

Tomato Fruitworm Damage

Tomato Fruitworm Damage

The tomato fruitworm is the most serious insect pest of tomatoes in the US, feeding on fruit and contaminating it with insect parts, excrement and decay-causing organisms. Interest in spraying insecticides to control the fruitworm was accelerated in the 1930s by the finding of insect fragments in canned products, which were seized and destroyed as adulterated foods by the FDA. Today, insecticides are used to prevent widespread insect damage to tomatoes and tomato shipments for processing are rejected if more than 2% damage is found. Therein is the dilemma. If the standard was relaxed (say to 4%), tomato growers could probably make one less insecticide spray. However, consumers may not want more insect fragments in canned tomatoes and may actually want a tighter standard which would result in more insecticide sprays.

“All loads of processing tomatoes in California are evaluated by inspectors from the Processing Tomato Advisory Board, a marketing order, under the direction of supervising inspectors from the California Department of Food and Agriculture. A load of processing tomatoes is rejected if 2% or more of the tomatoes by weight have a worm or excreta in the flesh of the tomato.

The damage tolerance acceptable to consumers and industry could be changed accordingly. Increasing the tolerance might be expected to result in a reduced number of insecticide applications when used in conjunction with a careful monitoring program.

A reduction in the tolerance might also be considered, arguing that consumers would not tolerate even the present level of insect fragments which, as our results indicate, is possible to have in the final product.”

Authors: Zalom, F. G., and A. Jones.
Affiliation: Department of Entomology, University of California, Davis
Title: insect fragments in processed tomatoes
Source: Journal of Economic Entomology. February, 1994. 87[1]:181-186.

Insecticide Use is Critical to Successful Tomato Production

Insect Damage: Tomatoes

Insect Damage: Tomatoes

Insecticides are generally used on close to 100% of tomatoes grown in eastern states to prevent damage from a large number of species that would feed directly on the tomatoes- significantly lowering their value. A study of tomatoes in Virginia revealed that uncontrolled insects lowered marketable yield by 33%. Insecticide cost ($230/A) prevented losses of from $3000-$7000/A.

“Insect pest management is critical to successful tomato production in the Mid-Atlantic U.S. Important pests each year often include the tomato fruitworm (= corn earworm), thrips, stink bugs, aphids, and spider mites.  Occasional pests also include armyworms, Colorado potato beetle, hornworms, cabbage looper, and leafminers. To control this complex of pests, insecticide usage is often intense on commercial farms. For instance, in Virginia, tomato growers make an average of 7 to 10 pesticide applications per crop.

Although IPM and biological control programs have been demonstrated, insecticides continue to be the chief management tool by which damaging insect pests can be controlled immediately and economically for conventional tomato producers. Because strict quality standards for produce coupled with high production costs are unlikely to change significantly, current and future tomato pest management strategies are likely to include an insecticide component.”

Author: Thomas P. Kuhar
Affiliation: Associate Professor – Vegetable Entomology, Virginia Tech
Title: Update on insect pest management for tomatoes
Source: 2011 Proceedings 56th New Jersey Annual Vegetable Meeting. January 11-13, 2011. Available at:

A Late Blight Pandemic Struck Northeast Tomatoes in 2009

Untreated Tomatoes

Untreated Tomatoes

Treated Tomatoes

Treated Tomatoes

The late blight fungus attacks all aboveground parts of the tomato plant. Infected foliage becomes brown, shrivels and soon dies. When severe, all plants in a field may be killed in a week or two. The spores can be disseminated up to 30 or 40 miles by wind or over short distances by dew and rain. Each spore may swim in a film of water on plant surfaces to initiate a new infection. A recent article summarizes the effects of a severe late blight outbreak in the U. S…

“Indeed, the tomato late blight pandemic of 2009 made late blight into a household term in much of eastern USA. Many home gardeners and many organic producers lost most, if not all, of their tomato crop. Some CSAs (Community Supported Agriculture) could not provide tomatoes to their members. …This pandemic was unusual. It started synchronously in mid to late June over much of the northeastern USA. The pathway was via infected tomato transplants shipped to the garden centers in large retail stores throughout the Northeast. …Many homeowners and organic growers lost crops when fungicide was not applied soon enough, and because they lacked highly effective curative fungicide options. (Conventional commercial growers, who have more fungicide options, were more successful in delaying the epidemic and subsequent yield loss.) …Later in the year other issues arose. Consumers were alarmed to see fungicide residues on tomatoes at farmers markets, especially on organically produced fruit. (Some copper-based fungicides are allowed in organic production in some states.)”

Authors: W. E. Fry, et al.
Affiliations: Cornell University
Title: The 2009 Late Blight Pandemic in Eastern USA.
Publication: APSnet Features. 2012.

Mildew Causes Sunburned Tomatoes

Mildew on tomato leaves

Mildew on tomato leaves

Powdery mildew on tomatoes is restricted to warm, arid and semiarid climatic regions. A fine talcum-like powder growth develops on the leaves resulting in the loss of 30-40% of the leaf canopy. Defoliation predisposes fruit to sunscald and reduced quality. The tomatoes become soft or are burned before they reach maturity.

“Powdery mildew is a serious economic problem in Mediterranean tomato production. The disease is currently controlled by fungicides (especially sulfur) in both conventional and organic production. In addition to causing reductions in yield and quality, it may make plants vulnerable to secondary infections by other fungal pathogens (e.g., Botrytis cinerea). Fungicides are used to control tomato powdery mildew, even in organic production, where sulfur fungicides are permitted and widely used.”

Authors: N. G. Dafermos, et al.
Affiliation: School of Agricultural Technology, Technological Educational Institure of Crete, Heraklion-Crete, Greece.
Title: Integration of Elicitors and Less-Susceptible Hybrids for the Control of Powdery Mildew in Organic Tomato Crops.
Publication: Plant Disease. 2012. 96(10):1506-1512.

Numerous Fungicide Sprays Needed in Brazil to Prevent Tomatoes and Potatoes from Rotting

Late Blight Tomatoes

Late Blight Tomatoes

The late blight fungus infects both tomatoes and potatoes. The fungus attacks all the aboveground parts of the plant. Infected foliage becomes brown, shrivels, and soon dies. When severe, all the plants in a field may be killed in a week. On tomato fruit, greenish brown greasy spots develop and can cover the entire tomato. Decaying vines can be identified by a foul odor. Environmental conditions in Brazil are ideal for the development of the disease.

“Tomato and potato are the most important vegetable crops in Brazil. During 2002, production of tomato and potato in Brazil totaled 3.6 and 3.1 million tons, respectively. The major producing areas are the south and southeast regions, in which 57.2% of the tomato and 92.3% of the potato are produced. Late blight, caused by Phytophthora infestans, occurs in both regions and is the most serious foliar disease of these crops. The environmental conditions in these regions also are highly favorable to late blight development, leading to severe crop losses if no control measures are adopted.”

“Due to favorable environmental conditions and high susceptibility to late blight, up to 20 and 15 fungicide sprays commonly are used in tomato and potato crops, respectively.”

Authors: A. Reis, F.H.S. Ribeiro, L.A. Maffia and E.S.G. Mizubuti
Affiliation: Departamento de Fitopatologia, Universidade Federal de Viçosa, Viçosa-MG, Brazil
Title: Sensitivity of Brazilian isolates of Phytophthora infestans to commonly used fungicides in tomato and potato crops.
Publication: Plant Disease. 2005. 89(12):1279-1284.

IPM Research in Turkish Tomato Fields Shows Importance of Fungicide Sprays

Tomatoes are a major vegetable crop grown in Turkey with an annual production of about 10 million tons. Fresh market tomatoes account for 80% of production while canned, dried and paste products from Turkey’s 55 tomato processing plants account for the remaining 20%. Late blight is a devastating disease of tomatoes for which Turkish farmers typically spray twice a season. However, IPM research has shown that 5 carefully-timed applications are much more productive.

“In 1997, Phytophthora infestans (Late Blight) caused an epidemic and great crop losses, especially in the Marmara and Trakya regions. Turkey, as a tomato paste producer, had to import tomato paste to satisfy the contracted commitments. IPM studies were conducted by Ege University, Faculty of Agriculture and Department of Plant Protection in Marmara Region (Bursa) during the years 2000-2005.”

“In all IPM programs, a total of 5 fungicide applications were made depending on which IPM program was followed. … The grower’s standard had two fungicide applications when first symptoms appeared. All of the IPM weather timed spray programs increased marketable tomato yields resulting in higher net economic returns to the farmer. The growers recognized how poorly their standard spray program yielded, resulting in lost income to their farm operation.”

Authors: H. Saygili, N. Tosun and H. Türküsay.
Affiliation: Ege University, Faculty of Agriculture, Izmir-Bornova, Turkey
Title: Integrated Disease Management in Processing Tomato in Turkey
Publication: Acta Horticulturae. 2007. 758.