Q. Many of the mango flowers on our tree turned black and we don’t see any fruit being set. Is this a disease and how do we cure it?
H.L., Hallandale Beach
The fungal disease called anthracnose causes mango flowers to appear withered and blackened, and therefore, reduced fruit set results. Periods of prolonged dew are the most likely culprit contributing to the severity of this common mango disease on your tree. Some varieties, such as Cogshall, Graham, Haden, Irwin, Julie, Kent, Mallika, Valencia Pride and Zill, are more susceptible than others.
In general, the Indo-Chinese/Philippine-type varieties are more resistant to anthracnose. This type tends to have mature fruit with green skins and is not as colorful as the Indian-type of mango that is more commonly grown in South Florida.
Control this disease by spraying a copper-based fungicide during flowering and continue throughout the growing season if anthracnose has been a problem on your fruit in the past. With plant diseases, it’s all about prevention since most fungicides don’t cure diseases. That’s why it’s important to protect the blooms and young fruit on mango varieties that are susceptible.
Liquid copper fungicides are available at garden centers and retail nurseries. The product must be labeled for use on dooryard (residential) fruit trees. Mix and use all pesticides according to label directions. Mixing in a spreader-sticker (if the fungicide label allows) helps to get better fungicide coverage. Removing dead or infected shoots and old flowers stems helps reduce the amount of fungal spores.
Spray when the first bloom spikes are two inches long. Repeat once a week as long as there are open flowers and until fruit is set. After fruit set, repeat once a week for three to four weeks.
When choosing a variety of mango that is not as susceptible to anthracnose, consult your county Extension office or ask a fruit nurseryman to suggest suitable varieties.
Send undamaged (live or dead) insects in a crush-proof container such as a pill bottle or film canister with the top taped on. Mail them in a padded envelope or box with a brief note explaining where you found the insects.
Do not tape insects to paper or place them loose in envelopes. Insect fragments or crushed insect samples are almost impossible to identify.
Send them to the address of your county extension office, found in the blue pages in the phone book under county government.