I’ve just returned from a wonderful trip to Switzerland. Spring was just budding forth when I arrived so the fields were full of wild flowers, tulips and daffodils.
The climate there is similar to Vermont where I was born and the landscape plants made me feel as if I was there. They have rhododendrons, lilac and other flowering plants in full bloom.
The crops included apples, pears and of course the grape vines of the many vineyards in the area. But the one thing that really surprised me were all of the European fan palms I saw. While most were in pots, many were planted in the ground and doing quite well. I saw a lot of bamboo in these same areas.
There are many soil rich deltas from the rivers swollen with the runoff of the Alps and these make for great crop lands. We can only buy soil in bags that would come close to the black earth of their farm fields. I could go on, but back to reality and South Florida.
While I was away, the royal palm bug came around town in a big way. I took a drive and out of 20 royal palms I looked at, two or three had signs of this bug. We had this problem a couple of years ago and this bug has a tendency to be sporadic when it comes to infestations. In fact, most years the damage from this insect is almost nonexistent. Natural controls which help keep the populations low include, heavy summer rains which wash them from the trees and also really cold winter temperatures. There are also predatory spiders which help with control unless their numbers are low. So we may be seeing higher numbers this spring due to a rather dry summer last year followed by a warm winter.
The damage from this bug is most severe in spring and early summer. The adults are less than 1/10th of an inch with tan to yellow bodies, red eyes and transparent wings. In other words hard to see. The nymphs are even smaller. The females lay one to two eggs a day along the midrib of the new leaflets. When they hatch, they feed inside of these still folded leaflets by sucking on the leaf tissue. This causes a stippling of the tissue followed by browning and finally a ragged appearance of the emerging fronds. If the populations are low this will result in aesthetic damage only. But with higher infestations this damage can result in a lower ability for the palm tree to photosynthesize for food causing a decline in health or even death of the trees. The aesthetic damage is also problematic because the damage is on the new growth which means you will have to look at the ragged fronds until they have migrated to the lower half of the canopy and finally are shed by the tree.
So what to do? You will have to treat with a systemic insecticide which can be applied by either spraying (hard if the tree is very tall), drenching the root system or injection of the trunk. Merit, Bayer Crop Science and Safari have all been proven effective. These systemic insecticides are also long lasting, from nine to twelve months. If you see this insect damage in your yard or neighborhood you could treat your palms to try and avoid severe damage. While you could apply an insecticide every spring to ward off any damage, this would probably be unnecessary most years. Especially if we have heavy summer rains or a very cold winter the year before.
Another insect making headlines in the horticultural world is the Spiraling Whitefly. You may remember the Ficus Whitefly which has been causing trouble with ficus hedges for the last few year but this one is different. It does not seem to be causing the severe plant damage or branch die back of its predecessor. Look for white spirals on the undersides of the leaves. There will be a buildup of a white, waxy substance as well. This waxy buildup can build up to amounts so great it begins to drip off the affected plants and onto cars, patios and pools causing a sticky mess. This honeydew is actually the insect’s excrement and can turn into what is referred to as sooty mold which will then turn black.
The best thing to do when you first discover you have this whitefly is to try and wash as much off the plant as possible with a strong stream of water. Follow this with a treatment of the same insecticides as mentioned for the royal palm bug. These can also be applied as a spray to the foliage, a drench of the roots or trunk injection. You can treat with an insecticidal soap or horticultural oil but you will have to reapply once a week for approximately a month for complete control. The systemic insecticides will once again last for up to a year.
For pictures of both of these insects visit the University of Florida, IFAS Extension web site.
Eileen Ward and her husband Peter have owned and operated Greensward of Marco, Inc., a lawn maintenance and landscaping company since 1981. Watch Eileen’s gardening videos on MarcoIsland-TV.com.