Update on anthracnose disease control
on lychee in south Florida

Jonathan Crane, Tropical Fruit Crop Specialist

Anthracnose is the major fungal disease of lychee in Florida and may reduce ‘Mauritius’ crop yields up to 100% in some years. Hot, humid, and rainy weather during fruit set and development are conducive to disease development. At present, ABOUND (azoxystrobin) is the only registered fungicides for the control of anthracnose pathogen (Colletotrichum gloeosporioides) on lychee (see below).  However, previous and current field research and registration efforts may result in additional registered fungicides in the near future.

Previous fungicide trials suggested frequent applications of benomyl (Benlate), mancozeb (Dithane M-45), or benomyl plus mancozeb were effective at disease control on lychee. However, a registration trial on benomyl found pesticide residues too high and the effectiveness too low to pursue this compound for registration.  During 1997, field research compared the effectiveness of tebuconazole (Folicure 3.6F) at two rates (4 oz and 6 oz material rates per acre), mancozeb (Dithane DF) at a 2.5 lb material per acre rate, copper hydroxide (Kocide 2000) at a 2.4 lb material per acre rate and a non-sprayed control.  Results found tebuconazole and mancozeb treated trees had a lower percentage of diseased fruit than copper and non-sprayed control trees.  More recently, azoxystrobin (ABOUND) was reported to be effective at controlling anthracnose. 

Fieldwork during 1995 found anthracnose disease spores survive on vegetative parts of the tree. These spores then spread and infect deteriorating or dead floral parts and young fruit by rain splash.  This indicates any effective spray program on lychee has to begin at flowering and prior to fruit set.

Hopefully, in the next year or so, we will have one or more additional efficacious fungicide materials available to alternate with ABOUND in an integrated disease resistance management program on anthracnose.

ABOUND Flowable (azoxystrobin) has been registered to control anthracnose on numerous tropical fruit crops including avocado, guava, lychee, mango, and papaya, just to name a few.  ABOUND may be purchased from local chemical companies and be sure to pick up a copy of the supplemental label (Adobe Acrobat required) from them or the Miami-Dade County Cooperative Extension Service.  As usual, you must have the label in your possession and follow all the label instructions on the main and supplemental labels.