How to prevent mango fruit drop

Q: My mature mango tree is fully grown 15 yrs old and each year it fully blooms, sometimes twice. Shortly thereafter, all the baby mangos and flowers fall off providing no mangos for the season. I have tried fertilizing, spraying the tree for fungus or other insects, to no avail. I give up, any suggestions?

A: Dropping fruit in pretty common issue with mango trees. There may be several reasons, or a combination of reasons.
1. Fungal disease (anthracnose), and/or powdery mildew. To avoid fungal disease problems, spray your tree when it just begins to form the flower spikes. Treat foliage with Copper fungicide. There is also another one, very effective for anthracnose: Thiophanate methyl.
2. Inadequate nutrition. Feed your tree with a combination of granulated fertilizer Mango-Food, liquid booster SUNSHINE Mango Tango and micro-elements Sunshine Honey and Sunshine Superfood
Check out pictures of our mango tree problems that were fixed within a month by using Sunshine Boosters.
3. Too much rain or heavy dew during blooming and fruit set (see 1 - use preventive treatment for fungus)
4. Cold. Sometimes the cause of premature fruit drop is from the cold weather during bloom and fruit set. Usually the most affected varieties are the early bloomers including Glenn, Haden. The cold damages the developing embryo in the seed. The fruit starts to develop but because of ethylene gas given off by the damaged embryo, the fruit is triggered to drop before maturity. To see if cold temperature was the cause for your fruit dropping, cut open the fallen fruit. Even if there is a small speck of brown in the seed, that's enough damage to stop fruit development.
To learn more how to care for your mango, please read this publication.

Plumeria cold protection

Q: We have a purple-flowering plumeria which resides on our sunny deck during the warm months and then Winter vacations on our back porch where we can close the plastic film windows and where it stays above 50 degrees (overnite) until it can get moved outside again. We live in zone 8+ in South Carolina and I would love to plant it outside. Do you think if we ghost-covered it when alerted that we would have an overnite freeze, that it would survive being planted in the ground and recover to flower when warm? I don't believe the soil in our yard has ever frozen below the top 1/2 inch or so, and never for more than a few hours at a time. What do you think?

A: Plumerias are tropical plants, which means, they need frost-free environment. Even if the ground is frozen only on "the top ½" or so"- this may be enough to kill the plant. From our experience, plumerias can withstand a few hours of windchill frost (not frozen soil), but even if they survive, they may get some branches damage, and recovery may take so long that the plant may not even bloom the next year. So I wouldn't take that risk even with a ghost-cover cold protection. We have customers who grow tropical plants in the ground in colder areas, but they have greenhouse protection: this means, the soil is warm and the air temperature is maintained above 45-50F. For example, this Greenhouse in Virginia.

We recommend to continue growing your rare plumeria in container and move it inside when temperatures drop below 50F (recommended) and for sure when they drop below freezing. Plumeria can take a cold night (a few hours of upper 30's) as long as it is followed by a nice warm sunny afternoon with at least upper 50s. Otherwise, keep it indoors. The good news is, since plumerias are deciduous and have no leaves in winter, low light level won't affect the plant.
Just make sure to minimize watering and keep the plant on a dry side until it starts growing new leaves in Spring. You may continue fertilizing once a week with half-doze of Sunshine boosters - Sunshine TotalFeed. This will maintain the plant healthy and prepare for the blooming season in Spring.

Grafted Guanabana - what is the trick?

Q:Should I buy grafted Guanabana or a seedling? It is a big price difference. I have heard that Annonas fruit within 3 years from seed, why do I need a grafted tree?

A: Annona muricata - Guanabana, or Soursop - is known as the best tasting Annona fruit. Many fruit lovers and gardeners want to have this tree in their plant collection, and the first question they always ask is: "How soon will it fruit? I can't wait to enjoy its deliciousness!"
Most Annonas start flowering and fruiting at a young age, 3-4 years from seed. Annona muricata seedling takes longer. You may read more information on how to grow Guanabanas from seed, even in a pot, even indoors - in Tropical Treasures Magazine issue # 7. Although it may take up to 15 years to see the fruit...
Now we have a solution to get this fruit sooner - a grafted tree! It will fruit within a year after planting. The secret of grafting Guanabana was almost lost (it's a tricky one to graft) and grafted plants were nearly impossible to find. Now we have them! Quantities are limited.
Keep in mind that Guanabana is very cold sensitive and won't tolerate even light freeze. However it is still relatively easy to grow even in subtropical areas: the tree is small, and if tree grown in ground, a simple cold protection structure can be built around it using basic wood or pipes (metal or PVC) and covered with plastic for a few weeks of cold weather. Grafted Guanabana is also a perfect choice for container culture (hand-pollinating maybe required).

Photo: This grafted tree was planted less than a year ago, and was covered in winter with cold protection for about 8 weeks. Within a year, it has 4 large fruit on it!