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Some pest problems to watch for in 2008
by Dr.Richard Lindquist, Senior Technical Manager

Happy New Year! Let’s see now. The dollar is in the dumpster, housing prices are sinking, home building is down, gasoline prices are high, heating oil and propane (the latter I can personally attest to) prices have skyrocketed, there’s an extreme drought in parts of the Southeast, fires (soon to be followed by mudslides) have devastated large areas of Southern California, and, oh yes, we are in yet another presidential election year.

All of these things can and will affect companies that produce greenhouse or nursery ornamental plants. But wait, that’s not all.Growers also need to deal with the more mundane issues of crop production, including insects, mites and plant diseases. On many crops these pest problems are quite predictable, so growers can anticipate and develop plans to deal with them.However, there always seem to be additional “new”pest prob- lems to confront. These can be in three categories:

1. Former bit players that suddenly assume a leading role. This may be due to pesticide resistance development, pesticide selection, production changes, use of biological controls, or some other factor.
2. Common problems on some crops expand their range to attack crops that were previously left alone. This may be because of changes in cultivars, pesticide selection and availability, or simply adaptation of pests to new host plants. This expansion to new host plants is especially common with plant pathogens.
3. Pests introduced from offshore.These pests normally arrive on imported plant material, but can be carried by wind (e.g.hurricanes) and non-plant materials. With the increasing worldwide transfer of plant material, expect more pest visitors, many of which will like it here and stay.

The following is a brief summary of some things to watch for in 2008 – and beyond.

Light Brown Apple Moth
The light brown apple moth, Epiphyas postvittana, or LBAM, an insect native to Australia, and already established in Hawaii, has been detected in California – the first find on the US mainland. The larvae of this moth feed on numerous host plants, more than 250 at last count, including ornamentals, and can cause severe injury to them.Based on biological data for this moth species, more than 80% of the US mainland has a climate suitable for its survival. According to people who crunch numbers in California, the potential impact on California agriculture from LBAM is in the $100 million range. Even though $100 million won’t buy as much as it used to, it is still an impressive amount.

Chilli Thrips
Thrips are problems because they’re hard to detect, they may transmit plant pathogens, and there are few effective chemical or biological controls. The most recent thrips species, also mentioned last year, with potential to cause widespread problems is the chilli thrips, Scirtothrips dorsalis. This thrips was detected in Florida in 2005, and has since been detected in other states, including Texas and Hawaii. Chilli thrips have a wide host range that includes numerous greenhouse, nursery and landscape ornamental (e.g.poinsettia) and food crops. Chilli thrips can also infest major crops such as cotton, soybean and peanut. They are mainly foliage feeders, causing leaf distortion, bud abortion and plant stunting. Unlike the western flower thrips, chilli thrips do not feed on pollen. Chilli thrips may be able to transmit several plant viruses, so the potential problems from this species are serious. How serious, you ask? Serious enough that USDA-APHIS has formed a Chilli Thrips Task Force, consisting of federal, state university and industry folks to develop plans to manage the little beast.

Fig Whitefly
Do we really need another whitefly to worry about? No, but they keep showing up anyway. One newly-detected whitefly in south Florida is the fig whitefly, Singhiella simplex. At this time the fig whitefly has been found on different Ficusspecies in landscapes and nurseries, but azalea is also listed as a host plant. How much should we worry about this whitefly? Who knows? Whiteflies, like many other insects, mites and plant pathogens have ways of adapting to different plants if given enough time. As an example, Paul Ecke Jr.used to tell the story that back when the Ecke Ranch first started growing poinsettias in Encinitas, CA, whiteflies were not problems on the crop. In fact, they did not even have a sprayer. Times certainly have changed.

Red Palm Mite
Last year we mentioned the increasing importance of tarsonemid (broad and cyclamen mites) and eriophyid (rust, gall and blister mites) mites. They have not gone away, and continue to be potential problems on many greenhouse and nursery crops. These mite species are microscopic in size and do not produce webbing. Eriophyid mites do not even look like “normal” mites. A hand lens is not powerful enough to see the mites. The only good way to detect them is after they damage plants by producing galls, or stunting, distorting and bronzing leaves. Other mites that sometimes appear are the false spider mites (Family Tenuipalpidae). They are called false spider mites not because they try to disguise themselves as spider mites, but because they do not produce webbing. Some members of this mite family are also called flat mites. Besides not producing webbing, false spider mites are slow moving and do not reproduce as rapidly as true spider mites. The cur- rent best known members of this group are the privet mite, Brevipalpus obovatus, and the Pacific flat mite, Brevipalpus pacificus. The privet mite has been collected from more than 50 genera of ornamentals, while the Pacific flat mite is mainly a pest of orchids. In addition to the above mites, there’s another species out there that will have an impact wherever palms are grown in the United States - the red palm mite, Raoiella indica. The first report of this mite in the Western Hemisphere was on the island of Martinique in 2004. In 2007 it was found in the US Virgin Islands, Jamaica and Venezuela. In addition to damaging many palm species, the red palm mite also infests heliconia, ginger, and bird of paradise. The next time you go on a Caribbean cruise and bring back some of those neat hats, bowls, or other handicrafts made with coconut palm leaves, you just might be bring- ing red palm mites as well. Probably not a big problem in states such as Michigan, but in Florida, Texas or California, it certainly could be a huge problem.

Other insects that might keep you awake at night
Mealybugs, including the pink hibiscus mealybug, Maconellicoccus hirsutusand the Madeira (as in “Have some madeira my dear”) mealybug, Phenacoccus madeirensis, are contin- uing to cause problems on numerous ornamental plants.These two are in addition to the common citrus mealybug, Planococcus citri. All mealy- bugs can be very hard to control if allowed to become well-established, but the Madeira mealy- bug seems to be to be the worst of the bunch. What all of this should tell you is to keep informed on the latest news related to insect, mite and plant pathogens, both old and new. You are intelligent enough to be reading this newsletter, so that is a good start – but there is much more detailed information out there in print and on the web.