University of Florida/IFAS Extension Director for Nassau County, Rebecca Jordi, answers questions about landscaping and gardening in northeast Florida.
QUESTION: My milkweed is often overrun by aphids. Does milkweed in the wild have the same problems and how, possibly, is it naturally controlled? PG
JORDI: First off, thank you for giving me the opportunity to inform people about the correct thing to do with their milkweed in the fall. Right now, we should cut the milkweed down as we need to encourage the monarchs to migrate. If we leave the butterflies and larvae a food source, they will stay and will most likely die when cold weather returns. In addition, if we leave the milkweed in bloom, it has a higher chance of developing the virus which ultimately kills the monarchs. This virus causes deformities and does not allow the monarchs to spread their wings and fly. So, please consider cutting the milkweed down and throwing the tops away. We will have plenty of opportunities to have more milkweed and butterflies next year.
To answer your original question – yes, native or wild milkweed do get aphids and we either spray them with a water hose to knock them off or let the beneficial insects reduce the populations for us. Of course, I take great pleasure in smashing them one by one with my fingers. Now, I know it sounds cruel, but I have no warm place in my heart for the plant sap-sucking little pests. One other important thing to know – we never recommend applying any type of pesticide on our wildflowers as we need to protect native pollinators (bees, butterflies, wasps, etc.).
QUESTION: I am re-sodding my lawn. I was told by my neighbor to ask you how often to water it. JD
JORDI: Well, give a hardy “thank you” to your neighbor. I just attended a conference where I learned the newest research indicates we should water newly establishing grass every day for 15 days for grass in full sun, then every other day for 15 days, then you should go to once a week during the cool season and twice a week during daylight savings time. Grass grown in shady sites or in dappled light need less water and fertilizer. Remember, we don’t fertilize here in Northeast Florida until April 15 using 15-0-15.
QUESTION: What is the white stuff growing on my persimmon? JH
JORDI: Thank you for bringing in clippings of your persimmon tree to the Yulee satellite office. The white stuff is an insect called scale. Both soft and armored scale can be pests of persimmon and other fruit trees. I suspect your scale is one of the armored scale species as we are seeing no honeydew or sooty mold. Those armored scale insects typically interested in persimmon are Hemiberlesia rapax, Greedy scale and White peach scale, Pseudaulacaspis pentagona.
All scale insects are controlled by the same method: monitor the tree and look closely at the scale. When the eggs and crawlers (immatures) are present use insecticidal soap, horticulture oil or other insecticide in two applications about 10-14 days apart. This is not a preventative method; the insects must be present for the chemical to work. Dormant oil will also control scale but generally is only used when temperatures are cool. You need to apply something now. As always, it is critical to follow the directions on the pesticide label.
Fruit Tree Tips
A few other important hints about fruit trees to consider. Remove lawn grass as far away from the tree as possible. What we do to lawns we should never do to any tree whether it is a fruit tree or an ornamental tree. Be sure mulch is not piled up against the tree trunk. Often fruit tree bark is thin and allowing mulch to accumulate around the trunk can easily contribute to disease entering the tree.
Do not over water. Once a week is sufficient in the early establishment of the tree but afterward, if we receive sufficient rain, the tree many not need to be irrigated. In addition, over use of high nitrogen fertilizers can cause the tree to be just too attractive to insects. Lastly, please consider purchasing persimmon varieties suitable for our climate. Astringent cultivars will not have a pleasant flavor unless allowed to ripen completely to the point their flesh becomes soft and almost gelatinous. Non-astringent cultivars can be eaten when fully ripe or while they still have an apple-like crunch. Both types of persimmons will grow and fruit well in North Florida. Oriental persimmons (astringent & non-astringent) are known scientifically as Diospyros kaki. The native species D. virginiana has smaller astringent fruits.
Rebecca L. Jordi
Nassau County Extension Director
UF/IFAS Environmental Horticulture
543350 U.S. Highway #1
Callahan, FL 32011