Fall 2011 (Volume 15, Issue 3) EDITOR’S NOTE EUROPEAN PEPPER MOTH: A NEW INVASIVE he focus of this issue is managing MOTH THREATENS CALIFORNIA AGRICULTURE insects and other pests in green- by James A. Bethke and Bryan Vander Mey T houses and nurseries, especially invasive exotic pest species. Two inva- alifornia growers should be on the The moth was first identified in Cali- sive moth species are discussed in the lookout for a new exotic pest, the fornia in 2005 and was originally as- feature articles: Jim Bethke writes C European pepper moth (EPM). signed an “A” rating, which meant that about the European pepper moth and Many people won’t think much of this when found, there would have to be Steve Tjosvold discusses insecticides action taken to eliminate the risk of for controlling light brown apple moth. insect because it’s just another moth, but In a new column, “Disease Focus,” if ignored, it could become a serious pest spreading the insect. Since 2010, the Deborah Mathews describes insects to on certain ornamental and agricultural insect has been found widespread in watch for that can vector plant viruses. crops. It has been a consistent pest of San Diego County and has been detect- In the regional reports, Jim Bethke greenhouse crops in Europe, but has not ed elsewhere in the state, as well as (San Diego) discusses palm weevils and been as destructive in field-grown crops. numerous other states, so a move to reniform nematodes, Steve Tjosvold EPM, Duponchelia fovealis Zeller reduce the severity of the rating is in (Santa Cruz/Monterey) writes about (Lepidoptera: Pyralidae), originates in the progress. Regardless of the rating, con- sudden oak death and Julie Newman Mediterranean area and the Canary Is- cern from ornamental and vegetable (Ventura/Santa Barbara) describes how lands, and also has been known to occur plant producers is leading to the for- growers can mitigate pesticide runoff in Africa and Asia Minor where it is a mation of a USDA APHIS Technical while managing invasive pests. Another significant pest of agricultural crops in- Working Group to study ways of re- new column is “Gleanings from Meet- cluding peppers, squash, tomatoes and ducing the impact that this pest may ings” in which we highlight past corn. The Animal Plant Health Inspection have on U.S. agriculture. UCNFA educational meetings. Finally, Service (APHIS) of the USDA originally included in this issue is an article on considered this moth an actionable pest The caterpillars are difficult to detect the use of filter strips (“Get Cultured”). because initially it was not known to oc- because they typically feed at soil level cur in the United States and because it is a around the crown of the plant and Julie Newman serious agricultural pest. sometimes burrow into stems. Prolifer- Co-Editor Inside This Issue Feature: European Pepper Moth: A New Invasive Page 1 Regional Reports: Moth Threatens California Agriculture San Diego County: Getting Serious about Palm Page 20 Feature: Field Evaluation of Insecticides to Control Page 6 Weevils Light Brown Apple Moth Ventura and Santa Barbara Counties: Mitigating Page 22 Pesticide Runoff While Managing Invasive Pests Get Cultured: Drainage Channels and Vegetated Page 11 Santa Cruz/Monterey Counties: Environmental Page 25 Filter Strips in Nurseries, Part II Conditions Could Be Monitored in the Nursery Disease Focus: Insect-Transmitted Plant Virus Page 15 to Limit the Spread of Sudden Oak Death Diseases New Publications Page 27 Gleanings from Meetings: ABCs of Fertilizer and Irrigation Management Page 17 Is Nursery Insurance Practical to Manage Risk Page 18 in Your Business? UCNFA News Page 2 ation of the population can occur with- Survey data to date confirmed the pres- tions from lepidopterists and official out notice. You should be aware of the ence of EPM in 16 counties in Califor- records from invaded countries in potential this pest has to do serious crop nia. Europe. damage and watch for it. The detection in July 2010 in San Die- Development from egg to adult is as One of our biggest worries during the go County was very extensive at one long as 47 days at 68ºF, but will be last poinsettia season was that poinsetti- production facility and caused the much shorter in our warmer climates as are on the host list. Unfortunately, County Agriculture Commissioner’s and especially in greenhouses. The we have observed larvae girdling poin- office to put a hold on all plants adult (fig. 1A) life span is from 1 to settia and causing significant damage throughout the facility. At a great cost 2 weeks, and a female can lay up to on some growers’ crops. That means to the company, it took approximately 200 eggs, singly or in small batches. that everyone growing poinsettias this two weeks of intensive treatment appli- Eggs are small (0.5 x 0.7 millime- coming season should be looking for cations and the destruction of mature ters), whitish to green in color and this moth and should consider initiating plants in order to release portions of darken to a reddish color as they age a preventative program or there may be the crops for sale and distribution. (fig. 1B). The adult forewings are unintended consequences. Younger plants were treated preventa- gray to brown with distinctive mark- We will do our best herein to educate tively. In all likelihood, growers of ings and a wingspan of .75 to .83 you about this insect so that when you EPM host plants here in the county inches (19 to 21 millimeters). The see it you will not be surprised and will have to monitor for the time being lowest lines on the outer wing have a hopefully will have some management and treat preventatively to remain moth tooth-like notch facing backward. solutions. We are studying the life his- -free (see host plants below). Males have a longer, more slender abdomen than females. Larvae are tory and control for this pest and plan to Life History have more results relatively soon. creamy white to brown with a dark There is little scientific literature from head capsule (fig. 1C) and lines of Invasion History which to develop a life history. Much distinct dark spots along the abdo- EPM was first detected in this country of what is known is anecdotal observa- men. Larvae mature in about 4 weeks. in 2005 as live larvae in a shipment of begonias from San Diego County. It was thought to be eradicated, but a de- tection in Canada in April of 2010 was traced back to ornamental plant produc- tion in San Diego County. Following action by regulators and treatment ap- plications by the grower and on the sur- rounding landscape by a commercial applicator, further surveys of the prop- erty could not detect any more moths or larvae. Unfortunately, a second detec- tion occurred in July 2010, and a trace- back led to the same area of San Diego County but to a different grower. This detection triggered an extensive trace forward survey to determine the extent of the invasion in California and other states. During the months of September and October 2010, APHIS and state departments of Agriculture confirmed the presence of Duponchelia fovealis in portions of 13 additional states includ- ing Alabama, Arizona, Colorado, Flori- da, Georgia, Mississippi, New York, North Carolina, Oklahoma, Oregon, Fig. 1. European pepper moth (EPM) adult male (A), eggs (B), larva (C) South Carolina, Texas and Washington. and pupa (D). Photos by J.A. Bethke and B. Vander Mey. UCNFA News Page 3 Mature larvae pupate inside a cocoon composed of web- erberry, goosefoot, kalanchoe, azalea, croton, poinsettia, bing and soil particles (fig. 1D). The cocoon is usually geranium (Pelargonium spp.), lisianthus, lilyturf, cuphia, attached to the undersides of leaves or the edge of the coleus, mint, mallow (Malva spp.), calathea, oxalis, pot, and larvae take about 1 to 2 weeks to hatch. The loosestrife, limonium, cyclamen, portulaca, ranunculus, number of generations per year is variable but is certain rose, bouvardia, heuchera, waterhyssop (Bacopa spp.), to be multiple generations in Southern California, where pepper (Capsicum spp.) and elm. Summaries of agricul- multiple year-round generations in greenhouse produc- tural plants that are attacked include celery, peppers, cu- tion is likely. We have started a colony in our green- cumbers, tomatoes, maize, pomegranate and certain house and have found the generations to be synchronous herbs. In San Diego County, confirmed host plants in- at this point, which may be an advantage for the timing clude begonia, echeveria, gerbera and several varieties of of applications. kalanchoe and poinsettia. I anticipate that the EPM host list will grow. Damage Control EPM causes severe damage to main stems, lower leaves and tissues that are adjacent to the potting soil. The lar- Control measures for adults include conventional regis- vae tend to create webbed tunnels and protective cover- tered pesticides applied where the adult will come into ings, and often feed below the soil line in soft plant me- contact with them. In addition, aerosols or fogs applied dia. Girdling damage can be seen on poinsettia (fig. 2A), in protected culture just before adults begin to fly at begonia (fig. 2B), kalanchoe (fig. 2C) and pepper (fig. night will be effective. In general, the adults are relative- 2D). ly easy to kill. Host Plants In contrast, the larvae are very difficult to contact with pesticides, and stomach poisons do not always reach the The host list is comprised of plants in about 38 plant feeding site. Therefore, some of the more effective com- families and include field-grown vegetables and orna- pounds against this pest will not be as effective as one mentals, greenhouse-grown ornamentals and herbs, and would expect.