Stephen J. Toth, Jr. and Thomas A. Melton, editors
Volume 17, Number 1, April 19, 2002

Fruit and Vegetables

From: Gerald J. Holmes, Extension Plant Pathologist

Pyraclostrobin is the active ingredient of a new fungicide developed by BASF Corp. The product has the trade names of Cabrio (fruits and vegetables), Headline (row crops) and Insignia (turf). BASF anticipated registration with U. S. Environmental Protection Agency in time for spring-planted crops. However, the registration process was delayed. BASF currently estimates registration by the fall of 2002. Cabrio, like other strobilurin-type fungicides (e.g., Quadris), has broad-spectrum disease control properties.

From: Frank Louws, Extension Plant Pathologist

On a case by case basis I have been working with agents to address problems with anthracnose ripe fruit rot that has appeared in many fields this spring. Fields first showed symptoms in the southeast of the state, then the northeast, and many more fields since with the onset of fruit ripening. Many growers are at risk, especially those who had plants diagnosed with anthracnose last fall (see Pest Alert, September 27, 2001). Contact your supplier to learn if your plant source may be at risk. Several suppliers have already alerted their growers.

Symptoms of the disease include typical sunken and round lesions with an orange discoloration within the lesion and brown spots on green fruit. The pathogen is named Colletotrichum acutatum. Symptoms appear to be distributed throughout the planting suggesting widespread distribution of the pathogen. This is discouraging because rouging of infected plants does not appear to be a viable option.

If warm and wet weather (especially with wind driven rains) occurs, then managing the disease will be difficult. If the weather cooperates, there is good potential to limit losses due to anthracnose. Recommendations for fungicide use were reviewed earlier (http://intra.ces.ncsu.edu/depts/hort/berrydoc/april5/index.htm and http://intra.ces.ncsu.edu/depts/hort/berrydoc/april11/index.htm) and again below.

Recommendations for Management:

1. If the problem seems to be associated with hot spots in the field, remove and destroy (bury or burn) infected plants and surrounding plants (5 to 10 foot radius). Regretfully, the problem appears widespread in most fields observed to date.

2. Avoid any overhead irrigation (e.g. for evaporative cooling) and do not over water or over fertilize (see Dr. Barclay Poling's April 17 summary at http://intra.ces.ncsu.edu/depts/hort/berrydoc/strawadv/).

3. Always pick the infested area last and do not let personnel or equipment move from an infested area to clean areas in order to limit spread of the pathogen.

4. Do not work plants when wet.

5. Although the economics are not available, it may be practical to pick and remove infected berries out of the field in order to reduce the amount of inoculum. However, be aware that this pathogen colonizes leaves and other green tissue without showing symptoms. Therefore, if the pathogen is on the fruit, it will also be on the plant tissue and it will be impossible to remove entirely. Removing infected fruit should help to reduce disease pressure.

6. Implement a vigilant Quadris + Captan fungicide program. If Quadris or Captan have not been used to date and if diseased fruit is present, it may take 14 to 20 days before a response to fungicide use is observed. Quadris and Captan have performed well in our fungicide trials and provide a fighting chance to limit crop losses. In our research we used a maximum rate recommendation of 12.4 fluid ounces per acre but the new label allows for 15.4 fluid ounces per acre. The 12.4 fluid ounces per acre rate has performed well in our trials and we do not have data to advise about the benefits of higher rates.

The following schedule is suggested:

In infested fields, implement a Quadris + Captan tank mix spray as soon as possible. Consider a second application in one week. Then apply Captan alone, followed by the tank mix again, and followed Captan alone. Do not apply more than two sequential sprays of Quadris and no more than four times per season (see the label). Under lower disease pressure, include Quadris (tank mixed with Captan) every 14 days and rotate with Captan (as recommended in Florida; in our trials, we see a benefit with the Quadris + Captan tank mix). See our 1999 and 2000 data. The use of Quadris and Captan ensure continuous coverage for anthracnose control and Captan offers gray mold control. Quadris is not very effective against gray mold (Botrytis). In fields with potential for heavy gray mold pressure, include Elevate or Switch with the Captan applications in rotation with the Quadris + Captan sprays. Switch may offer a limited amount of anthracnose control. Elevate is strictly a botryticide. Oxidate is a product heavily promoted for quick control. Regretfully, there is very limited data publicly available. In discussions with plant pathologists in other states who have conducted tests on other crops, results have not been highly encouraging. At this time, reliance on Oxidate alone is likely inferior to a program that would include Quadris.

For more information, contact your local Extension agent through the county Cooperative Extension Office.

To review a history of anthracnose problems in North Carolina and associated recommendations, visit the following sites on the Internet:

Berryagent notes distributed by Dr. Poling (Spring 2002):
http://intra.ces.ncsu.edu/depts/hort/berrydoc/april5/index.htm
http://intra.ces.ncsu.edu/depts/hort/berrydoc/april11/index.htm

1999 Infected Transplant Problems:
http://ipm.ncsu.edu/current_ipm/alert13.html
http://ipm.ncsu.edu/current_ipm/alert14.html

Information on the 2000 fruit rot problems:
http://ipm.ncsu.edu/current_ipm/palert27.html

Information on the 2001 fruit rot problems:
http://ipm.ncsu.edu/current_ipm/01PestNews/01News2/fruitveg.html
http://ipm.ncsu.edu/current_ipm/01PestNews/01News3/fruitveg.html

Disease Alert Concerning Anthracnose in Strawberry Plug Plants, September 27, 2001:
http://ipm.ncsu.edu/current_ipm/palert35.html

Alert of Full Quadris Label available in North Carolina 2001:
http://ipm.ncsu.edu/current_ipm/palert36.html

Summary of Fungicide Efficacy Data, 1998 to 1999:
http://www.smallfruits.org/Louws.htm

Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Last modified on April 22, 2002 by Stephen J. Toth, Jr.