Tomato Foliar Disease Online Demonstration

Foliar disease can cause severe damage to tomato in home gardens and commercial plantings.  In any given year, disease incidence may vary from minimal to severe.  Weather and environmental conditions are major determining factors of the severity of these diseases.  These diseases are caused by several microorganisms which may include fungi or bacteria.  More discussion of specific diseases in Oklahoma is provided at http://entoplp.okstate.edu/Pddl/advisory.htm (see vol. 9, No. 9).  Although the appearance of these diseases is very disheartening to a gardener, and potentially very costly to a commercial grower, this is a problem that can often be managed with proper preventive practices. 

How do you prevent these diseases?  The use of a variety of recommended cultural practice can help with foliar disease control.  Examples are proper plant spacing, variety selection, and general sanitation in and around the garden.  However, the primary practice is the proper use of fungicides.  This include choosing the right products and applying them at the correct time.  The correct time to begin fungicide application is before any disease symptoms are observed.  A good rule is to begin application when flowers are first observed.  Many growers wait until lesions are observed before making their first application.  Fungicides a generally considered to be protectants that prevent an infection from getting started.  With a few exceptions, fungicides are not very effective for stopping infections that have already been established.  Therefore, fungicides applied after a disease is already present may represent little more than wasted time and expense.

The objective of this project is to demonstrate the use of fungicides at two locations in Oklahoma.  These locations are the Lane Research Center at Lane, (southeast Oklahoma Atoka County) and, in the northeast, the Oklahoma Vegetable Research Center at Bixby (northeast).

Tomatoes of the variety Solar Fire were planted at each location. 

To appreciate the development of disease in tomato and other vegetables one must view the progression of the disease symptoms from the time of the first symptoms.  This may often follow a period of overcast and/or rainy weather. For this reason we will present frequent updates on the status of crop growth and disease incidence.  We will apply the fungicides listed below based on the following criteria:

Fungicides: the fungicide treatment will be a mixture of Chlorothalonil (the chemical name for products such as Daconil, Chlorothalonil, Bravo and others) and Bordeaux mixture.  The reason for this mixture is that Chlorothalonil is most effective on fungi while Bordeaux is a copper product and is most effective on bacterial diseases.

There will be three treatments as follows:

1.      No fungicide – a control treatment

2.      Fungicide applied at the beginning of flowering and then applied weekly

3.      Fungicide applied after disease symptoms are observed on the plants

Select sites individually to view crop progress and disease observations:

Choose one:         Bixby       Lane    Other Tomato Problems