For those of us who dwell in zone 10 year round, the late summer (August through September) is our “dormant” season. The temperatures and humidity is so high then, without even a night time respite for your plants that many just stall. “Stall” is the technical term a grower uses for an uncooperative plant, one that despite your best efforts in providing an optimal environment for growth, they just won’t grow right. They are stalling because they know that the world for them is unfriendly in September’s Zone 10 garden. The humidity makes precious new growth and bloom susceptible to disease, mildews, canker, and fungus. So, as a measure of self-protection, they just postpone (or stall) their growth or bloom until the temperatures moderate.
This give us a window of time, I usually suggest it occurs between Labor Day and Halloween, where as we are cooling down, our Zone 10 gardens offer a second spring. Unlike northern climes where summer ends with the first of several successive frosts, we are blessed with a period of time that, although variable in length we can anticipate a flush of growth as the plants make up for their late summer stall. The result, unfortunately, is that all the pests that enjoy noshing on soft green flesh of new growth also get a second spring! So this calls you to scout aggressively for problems, get them corrected timely so that as we continue toward nights that cause a cold-induced stall, your garden is in it’s best condition to weather the stresses of fluctuating cold (another unique challenge of Zone 10 gardening).
What are you on the look-out for? Aphids and mealy bugs have been the traditional challenge. Mealy bugs are the fuzzy white creatures that populate the growing tips of a plant, or around an emerging bloom. The Pink Hibiscus Mealy bug http://entnemdept.ufl.edu/creatures/orn/mealybug/mealybug.htm (under its coat of white waxy armor, the bug is pink. It will attack any color hibiscus, and many species beyond hibiscus) is particularly aggressive and was discovered inSouth Florida in 2002. By 2007 it had made its way toTexas. But all varieties are inspired to feed, so be on the lookout.
Aphids come in many shapes and forms as well http://edis.ifas.ufl.edu/pdffiles/MG/MG00200.pdf as do the infamous “white flies”. Please keep in mind however that everything that flies and is white is NOT white fly! Often it can be a beneficial wasp, or the male mealy bug. So look closer for the evidence of damage to your plant. An infestation with any of the piercing sucking pests we have discussed leads to distortion of the plants leaves (especially new growth) and or buds, presence of the pests (look under and down into emerging leaves)and often the tell-tale sign of black sooty mold and even ants. The ants love to eat the sugary excrement of these pests and have even been observed to keep aphids like we keep dairy cows. That sugary excrement also provides the growth media for the mold. Copious amount of black sooty mold that seems to appear overnight might be an indication that you have the invasive Spiraling Whitefly http://miami-dade.ifas.ufl.edu/documents/Thegumbolimbospiralingwhiteflyfactsheet.pdf on your hands.
Though also known as the Gumbo Limbo White fly, here on the TreasureCoast, we have observed the lion’s share of damage on palms. This makes it tough to catch since the beast is above your head. This invasive pest should not be confused with its predecessor, the Ficus White Fly http://miami-dade.ifas.ufl.edu/pdfs/urban_hort/The%20Fig%20Whitefly%20(AUG2008)%20Fact%20Sheet.pdf which attacks several species of ficus plants. I have also seen this one move to tomato plants, so keep learn how to spot it. The flying insect is not the problem it is the young-ins that will eat you out of house and home! Any of these beasts can be best controlled with a systemic insecticide that is distributed to all the plant’s tissue, poisoning the beasts as they feast on your plants (kinda satisfying isn’t it?) While this is a very responsible tact to take since the application of conventional chemical is only on the affected plants, some folks choose to avoid conventional approaches when ever possible. For them, the key is a solid maintenance program to support the plant’s natural defenses, and then some Neem Oil to treat flares of infestation.
Two more invasive species that rear their heads in this second spring are the Sri Lankan Weevil http://ipm.ifas.ufl.edu/pdf/Sri%20Lanka%20weevil.pub%20(Read-Only).pdf and the Asian Citrus Psyllid (ACP) which carries citrus greening disease and require a slightly different approach. The Sri Lankan weevil is usually identified when it drops out of an infected plant onto you as you pass under. You immediately notice it isn’t like anything you’ve seen before-it’s a “white beetle”. Look closely at the leaves of the tree and you will see notching along the edges, where they have been feasting. The problem is not so much how they eat the leaves of your trees and shrubs, there is little long term damage from that. The problem is with the hatchlings that develop underground feeding on roots in their larval stage. Unfortunately, there has not been a lot of research on this particular pest, so IFAS has made no recommendation for management. We have noticed success with the use of a combined product used on turf. It provides season long systemic protection from leaf feeding as well as under-the- surface control of grubs.
The Citrus Psyllid http://entnemdept.ufl.edu/creatures/citrus/acpsyllid.htm is the latest threat toFlorida’s Citrus industry, and it is probably in your back yard. The problem is, one cannot treat a fruit tree with a chemical pesticide that deposits in all the tissue of the plant. That would include the fruit, and when you eat the plant you will be consuming the toxins. So here, prevention is key! A routine (Every 10-14 days during active growing seasons) application of chealated citrus nutrition in combination with SuperThrive and delivered in a parafine horticultural oil is the homeowners close equivalent to what large scale groves are doing to protect their trees. Scouting your trees for the distinct form of these pests on the underside of your citrus tree leaves is an important responsibility if you choose to keep dooryard citrus. As homeowners, we need to support the citrus industry in fighting this pest. If we fail to, don’t be surprised if we lose the privilege of keeping citrus trees to the influential citrus lobby. Just remember how they were granted the authority to come into your yard and take your tree during the canker outbreak. Neem Oil and perethrins have some effect with direct contact, so be sure to spray the underside of the leaves where theACP likes to hang out. They fold their wings together, giving them the profile of a Sunfish sail- very distinctive—but tiny! And remember, not all of them are carrying the virus, so keep on eye on your tree for symptoms of disease. It must be removed an burned if you find it.
There are many more pests I could talk about, but the cool morning air is calling me to my garden for a fairy hunt. I will have to take my leave. . .