Cause:
Colletotrichum coccodes, C.dematium, and C.gloeosporioides cause anthracnose on tomato. C. coccodes is most prevalent, but anthracnose is not common in the Pacific Northwest. Fungi overwinter as microsclerotia, often in association with plant debris.
Microsclerotia can survive long periods in soil, producing conidia during moist conditions that also favor infection. Fungi may attack fruit that touch the soil or may be splashed on fruit or foliage. In wet weather, spores produced in spots on fruit are splashed by rain or spread by pickers to infect other fruit. Overhead irrigation favors disease spread. Infection is favored by free moisture and
temperatures between 50 and 86oF.
Symptoms:
Spotting on fruit is the major symptom; however, leaves, stems, or roots also may be infected. Fruit may be infected when green and small but show no evident spotting until ripening. Fruit becomes increasingly susceptible as it approaches maturity. Root infection is primarily in greenhouses and becomes evident as fruit begins to ripen.
At first, infected fruit have small, slightly sunken, circular spots. Spots grow to about 0.5 inch in diameter, darker with concentric rings, and more concave. Centers are usually tan and may have numerous dark specks (microsclerotia). Flesh beneath a lesion can be a lighter color than surrounding tissue. In warm weather, the spot soon penetrates into the fruit, which becomes worthless.
If leaves are infected, small, circular, dark areas of dead tissue, often surrounded by yellow halos, are evident. The oldest leaves are the most commonly infected. Roots may have brown lesions and will contain microsclerotia as they rot. Because of root damage, diseased plants are easily pulled from the soil.
Cultural
control:
Rotate at least every other year with a nonsolanaceous plant.
Irrigate only as needed, never in excess.
Use mulches, and stake plants.
Remove and destroy infected fruit (prevents buildup of soil population).
In greenhouse production use pathogen-free soil, prevent root injury, and avoid closed-recirculation irrigation-fertilization systems.
Chemical
control:
Bravo Ultrex at 1.8 to 2.6 lb/A at 7- to 14-day intervals.
12-hr reentry.
Cabrio EG on 7- to 14-day intervals at 8 to 12 oz/A or at 8 to 12 oz/100 gal spray volume (dilute). Use higher rate and shorter interval when disease pressure is high. Do not make more than one application of Cabrio EG or other Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. Preharvest interval is 0 days. 12-hr reentry.
Cuprofix Ultra 40D at 1.25 to 3 lb/A on 5- to 10-day intervals. 12-hr reentry.
Echo 720 at 2 to 3 pints/A on 7- to 14-day intervals beginning at fruit set. Preharvest interval is 0 days. 12-hr reentry.
Flint (Group 11 fungicide) at 3 to 4 oz/A on 7- to 10-day
intervals for disease suppression. Do not apply within 3 days of harvest. 12-hr reentry.
Kocide 2000 at 1.5 to 3 lb/A or Kocide 3000 at 0.75 to 1.75 lb/A on 5- to 10-day intervals. 24-hr reentry.
Maneb 75 DF at 1.5 to 2 lb/A. Do not apply within 5 days of harvest. 24-hr reentry.
ManKocide at 2.5 to 5 lb/A on 3- to 7- day intervals. Do not apply within 5 days of harvest. 24-hr reentry.
Nu Cop 50 WP at 2 to 3 lb/A on 7- to 10-day intervals. Do not apply within 1 day of harvest.
24-hr reentry.
Quadris at 5 to 6 fl oz/A on 7- to 21-day intervals. Do not apply until 21 days after transplanting or 35 days after seeding. Do not apply with an adjuvant due to possible phytotoxicity. Do not apply more than one (1) foliar application of Quadris or other Group 11 fungicide before alternating to a labeled fungicide with a different mode of action May be applied the day of harvest.
4-hr reentry.
Quadris Opti at 1.6 pints/A on 7- to 21-day intervals. Do not apply until 21 days after transplanting or 35 days after seeding. Adjuvants should not be used as they may increase the potential for severe phytotoxicity. Do not make more than one (1) foliar application of Quadris Opti or other Group 11 fungicide before alternating to a labeled fungicide with a different mode of action. Quadris Opti should not be applied within +/- 6 days of a postemergence broadcast application of Sencor. Preharvest interval is 0 days. 12-hr reentry.
Revus Top at 5.5 to 7 fl oz/A on 7- to 10-day intervals. Do not make more than two (2) foliar applications of Revus Top before alternating to a labeled fungicide with a different mode of action. Do not use on varieties in which mature tomatoes will be less than 2 inches. Preharvest interval is 1 day. 12-hr reentry.
Tanos at 8 oz/A starting prior to disease development on 5- to 7-day intervals. Must be tank-mixed with an appropriate contact fungicide with a different mode of action (e.g. mancozeb, chlorothalonil etc.). Do not apply within 3 days of harvest. 12-hr reentry.
References:
Jones, J.B., J.P. Jones, R.E. Stall, and T.A. Zitter. 1991. Compendium of Tomato Diseases. St. Paul, MN: APS Press.
Content edited by:
Cynthia M. Ocamb on
January 1, 2009
