Saturday, June 23, 2018
Home and Garden

Dr. Hort: Fruitless mangoes, yellowing gardenia

Fungi can affect fruit of mango tree

Q: We had a mango tree planted in our back yard in 2001. It is planted on the north side of a larger loquat tree. Every year, it flowers as in this picture taken in January. It keeps only one fruit a year, and it does not taste good. Is there something we can do so it can bear fruit?

Joseph DeBono, Dunedin

A: There are hundreds of varieties of mangoes, some sweet and juicy, some stringy, and others have a turpentine smell, so the flavor is part of the variety.

The fruit setting problem has more to do with several fungi collectively called anthracnose that kill the flower before it sets a fruit. Mangoes produce many more male flowers than female, the reason that it appears to have thousands of flowers, but only a few hundred are capable of producing a fruit. Second, the parasitic fungi turn the flower stalk black, killing the flowers before fruit can be set. The anthracnose fungi will also produce black spots on the fruit later in the season, which begin rotting the fruit.

To retard the growth of the fungi, spray the creamy-white blooms with copper or neem oil sprays weekly, through the blooming season. Also, prune branches where disease already has claimed the flowers, and a new bloom cluster (panicle) should reappear, a perfect time to spray, producing mangoes the second time around.

Gardenia bush is in poor health

Q: I have a very old and large gardenia bush at my home in south St. Petersburg. It always looks undernourished and sick. The flowers have no aroma and are very small, if any flowers appear at all. I cut it back near the ground awhile back, and the new growth there really pushed out some large green, shiny and healthy leaves, which now are starting to look sickly. My landscaper put down some sulfur, which he said it needed. That didn't help. Before I pull the thing out, I would like to know if you have any suggestions to bring it back to health. Without a good reason, I would really dislike killing this venerable plant.

Arthur Doyle

A: You may have pretty much ended any chance of survival. By cutting it so low, you probably cut it below the graft, in which case the more undesirable rootstock is suckering out. It is probably best to cut your losses and purchase a new one from gardenia specialists Carroll's Nursery, where you'll find several varieties to choose from.