- Author: Heather Scheck, Santa Barbara Ag Commissioner's Office
- Author: John Chitambar, California Department of Food and Agriculture
- Author: Surendra K. Dara, UCCE
A downy mildew caused by the oomycetous fungus, Peronospora mesembryanthemi Verwoerd has recently been confirmed by the USDA -APHIS from a red apple ice plant sample collected in San Diego. Since its first finding in San Diego County last summer, the disease has spread to Orange, San Bernardino, and Ventura counties and is now found in the Goleta area in Santa Barbara County. Peronospora mesembryanthemi was first reported from South Africa (Verwoerd, 1924) and later in the United Kingdom (Francis and Waterhouse, 1988) and New Zealand (McKenzie and Dingley, 1996), but has never been reported in North America. The host range of P. mesembryanthemi is thought to be limited to ice plants and it is currently found infecting the red apple ice plant, Aptenia cordifolia, the trailing ice plant or the pink carpet, Delosperma (syn. Mesembryanthemum) cooperi, and Lampranthus sp. in California. Both these ice plant species are native to southern Africa. Because of their environmental hardiness, ease of growing, and bright, colorful flowers, ice plants are grown as ornamental plants or found as groundcovers. However, the red apple ice plant is listed as an invasive plant by the California Exotic Pest Plant Council. It can sometimes grow like a weed.
Red apple ice plant overwhelming yucca plants. Photo by Heather Scheck, Santa Barbara Ag Commissioner's Office
Pathogen: Downy mildew appears as a mat of grey, blue, or brown fungal growth on the lower or both sides of leaves and other infected plant parts. Fungal growth consists of the asexual fruiting structures known as sporangia that are produced on sporangiophores, which are specialized hyphae. Downy mildew fungi cause systemic infection and grow internally in all plant parts. Infection rapidly spreads under cool and wet conditions. Windblown rain or sprinkler splashing spreads disperse sporangia and aid in the disease spread. Downy mildew fungi are obligate parasites of plants and most of them have narrow host range of one or just a few hosts.
Greyish sporulation of Peronospora mesembryanthemi on an ice plant. Photo by Jose Rodriguez, Soil and Plant Laboratory, Inc
Damage: The rapid spread of P. mesembryanthemi through southern California could be from accidental movement of infected nursery stock. Severe damage with heavy or total loss of plantings is becoming common in southern California counties where the disease is currently found.
Management: There are relatively few fungicides effective against oomycetous fungi and control can be very difficult. Since most of the fungicides are fungistatic (inhibit the fungal growth) rather than fungicidal (kill the fungus) against P. mesembryanthemi, fungicidal treatments only suppress the fungus, but systemic infections cannot be cured. Downy mildew fungi evolve very quickly to form new races and can rapidly develop fungicide resistance. (Is this sentence necessary? It is scary.)
Good cultural practices and sanitation can prevent or minimize downy mildew of ice plants. Some management options include:
- Prune plants regularly and remove weeds to improve air circulation and reduce fungal growth.
- Avoid overhead irrigation during cool weather.
- Consider watering in the morning hours so that plants dry during the day.
- Do not over- or under-fertilize as it may increase the chances of infection.
- Monitor highly susceptible species like the red apple ice plant and remove and destroy plants with symptoms of infection.
- Consider other host plants as groundcovers when replacing diseased ice plants.
Chitambar, J. 2016. Peronospora mesembryanthemi. (http://blogs.cdfa.ca.gov/Section3162/?tag=peronospora-mesembryanthemi)
Francis, S. and G. Waterhouse. 1988. List of Peronosporaceae reported from the British Isles. Trans. Brit. Mycol. Soc. 91: 1-62.
McKenzie, E.H.C. and J. M. Dingley. 1996. New plant disease records in New Zealand: miscellaneous fungal pathogens III. New Zealand J. Bot. 34: 263-272.
Verwoerd, L. 1924. Peronospora mesembryanthemi n. sp., die oorsaak van ‘n donsige skimmelsiekte van Mesembryanthemum-soorte. Ann. Univ. Stellenbosch 2A: 13-23.
- Author: Donald R. Hodel
- Author: James E. Henrich
- Author: Kenneth J. Greby
- Author: Gevork Arakelian
The Erythrina stem borer (ESB) (sometimes known as the Erythrina twig borer) (Terastia meticulosalis), a potentially devastating pest of Erythrina spp. (coral trees), has been sighted numerous times in southern California in the latter half of 2015 from San Diego to Ventura. Erythrina, a member of the Fabaceae (formerly Leguminosae, bean family) encompasses about 112 species (Bruneau 1996) and includes some of our most useful, valuable, well adapted, and spectacular flowering trees, adorning landscapes along the coast and adjacent plains and valleys in southern California. Indeed, a famous planting of E. caffra adorning the broad median of San Vicente Boulevard in Santa Monica and West Los Angeles was designated an exceptional planting (Hodel 1988). The plethora of sightings suggests a more recent introduction but the ESB was recorded as early as 1973 at Fort Piute in the California desert north of Needles near the southern tip of Nevada (CMSD 2016).
The ESB is of special concern for us because so little is known about its management and it appears to be especially destructive on coral trees, infesting seeds, destroying branch tips, and even killing whole plants. In Florida where it is native, it is a serious pest of naturally occurring and exotic coral trees, which are valued for agriculture, medicine, and landscape ornament (Powell and Westley 1993). Indeed, the cultivation of exotic coral trees in Florida is essentially impossible because of the ESB (Raven 1974); the only coral tree that can be cultivated reliably there is the native Erythrina herbacea, which likely co-evolved with and is found over most of the range of the ESB. In California the ESB has been observed so far on E. × bidwillii, E. chiapasana, E. coralloides, E. crista-galli, and E. falcata; other species will likely be added in the future. Although much remains to be know about the ESB in California, at least at this early stage, the ESB seems to prefer species of coral trees with more lender stems and slender regrowth of larger-stemmed species.
Fortunately, another serious pest of coral trees that is sympatric and co-evolved with the ESB, the Erythrina leaf roller (Agathodes designalis), has not yet been detected in California. The Erythrina leaf roller and the ESB are in closely related genera that have tended to niche-partition the coral tree resource to reduce inter-species competition (Armstrong and McGehee 1980, Sourakov 2011).
Much remains to be known about the natural history of the ESB, and the summary we provide here of its taxonomy, identification, distribution, and life cycle and damage it inflicts on coral trees is mostly from Arakelian (2016), Sourakov (2011, 2012, 2013), Sourakov et al. (2015), and our observations of infested coral trees here.
The ESB is one of five species in the largely tropical moth genus Terastia, which ranges from the Americas to Africa, Asia, and the western Pacific (Sourakov et al. 2015). The ESB is the only species of the genus native to the Americas. The other four species are T. africana, T. egialealis (Africa), T. margaritis (India), and T. subjectalis (Asia and western Pacific).
The adult ESB is a small-sized, brownish moth with mottled forewings and whitish hindwings with dark margins. Varying in size, adult forewing wingspans range from 2.5 to 4.6 cm, and the mottled body from 1.5 to 2.5 cm long, the latter with conspicuous knobs toward the posterior (Sourakov et al. 2015). In Florida the ESB varies greatly in size, which largely depends on the seasonal generation and diet. The spring generation, which feeds mostly on seeds, is larger than the fall and summer generation that feeds inside of stems. For example, wingspans of the spring generation average about 3.7 cm while those of the summer and fall generations average about 3cm and 2.5 cm respectively (Sourakov 2011). When at rest, the mottled- or marble-brown forewings are effective at camouflaging the ESB but when the wings are spread the white hind wings are conspicuous. Males and females are similar but the latter has more beige-brown forewing markings. In live specimens, the knobby abdomen is held in a curved, upright position, mimicking a praying mantis head, which is possibly a deterrent to predators (Sourakov et al. 2015). Eggs of the ESB, typically laid singly in the axil of leaves near stem tips, are translucent, white, delicate, dome-shaped with a reticulated surface, and about 0.8 mm long (Sourakov 2012). Young larvae are minute, about 0.5 mm long, and probably burrow directly into the flower, stem, or sometimes even a leaf petiole and then follow it to the stem. Larvae of the ESB are translucent and brownish white or cream-colored with a black sclerotized head and a dark sclerotized prothoracic plate that becomes lighter as the larva matures. Mature larvae are about 4 cm long. Larvae turn pinkish before pupation, especially when they complete their development on seeds. Pupae are cigar-shaped, light brown, and enclosed in a loose, double-layered cocoon (Sourakov 2011).
Endemic to the Americas, the ESB occurs from South Carolina to Florida and west to Arizona (and now California) in the United States and south to Argentina. Although recorded from Hawaii (Swezey1923, Zimmerman 1958), this report is now thought to be misidentification. Numerous publications list it as part of African or Asian faunas, but that misconception has been recently clarified (Sourakov et al. 2015), and it seems to be a strictly New World species, with superficially similar but genetically distant relatives in other tropical regions.
Life Cycle and Damage
Larvae of the ESB likely emerge through the ventral surface of the egg and tunnel directly into the plant (Sourakov2012). The downward-boring larvae feed on stem tissues as they go, hollowing out the stem and causing a characteristic dying-off of stem tips, which turn black and sometimes collapse. The entire upper and lateral sides of the plant canopy can be killed. This damage acts like pruning, forcing out new lateral shoots below the damaged area; these, in turn, can become infested and killed. Entire plants can be killed although this can take up to several years. In Florida after killing off stem tips in the spring, the last instar larvae move into seed pods, a condition which appears to be less common in California so far. Feeding on the red seeds typically causes larvae to accumulate reddish pigments, changing their color to pink before they pupate. In contrast, summer and fall generations feed inside the stem and do not feed on the hardened seeds; thus, they are typically paler in color and do not take on the pinkish hue. Larvae typically purge the hollowed out stem of frass by crawling backwards to the entry hole to defecate (Sourakov 2013). Full grown larvae descend from a silk thread to the ground and construct their cocoons in leaf litter to pupate. They have also been found in cocoons in old dead flowers at the ends of dead stems or inside folded up living leaves on the plant (Sourakov 2012). Adult ESBs are good fliers and can hover in flight similar to that of the Sphingidae (sphinx moths) (Sourakov 2012). This flight ability, along with larval endophagous feeding habits that provide some protection from predators, parasites, and abiotic mortality factors, largely explains why the ESB has been so successful in infesting Erythrina plants (Sourakov 2012).
Unfortunately, next to nothing is known about the management of the ESB. Nearly all attempts at post-infestation eradication in Florida have failed. Virtually nothing is known about resident natural enemies although they must be present; until they are identified biological control holds little promise. Perhaps vigilant scouting, judicious and immediate removal, bagging, and disposal of infested shoot tips, and ground and foliar treatment with systemic pesticides might be effective and justified for rare, exceptional, and/or noteworthy and valuable coral tree specimens. Because the ESB pupates in leaf litter on the ground, thorough raking and disposal of fallen leaves might reduce regeneration and provide some control. Cover/barrier insecticides, like pyrethroids (permethrin, cyfluthrin, bifenthrin) or emulsifiable concentrate formulation of carbaryl, might work well in killing of newly hatched larvae when they attempt to bore into the stems; although not yet tested for ESB, they have relatively long residual effects and might be effective. Further work is needed on this pest that poses a serious threat to California's ornamental landscape coral trees.
We thank Andrei Sourakov of the University of Florida for reviewing this paper and providing some of the images. Readers interested in supporting his important work can contact Andrei directly (firstname.lastname@example.org).
Arakelian, G. 2016. Erythrina Stem Borer (Terastia meticulosalis). L. A. County Dept. Agri.Comm. /Weights Measures Pest Note.
Armstrong, R. A. and R. McGehee. 1980. Competitive exclusion. Amer. Naturalist 115: 151-170. Bruneau, A. 1996. Phylogenetics and biogeographical patterns in Erythrina (Leguminosae: Phaseoleae) as inferred from morphological and chloroplast DNA characters. Syst. Bot. 21(4): 587-605.
CMSD. 2016. California Moth Specimens Database. On-line: https://essigdb.berkeley.edu/cgi// calmoth_query?stat=BROWSE&query_src=eme_BrowseCalmothNames&where- genus=Terastia. Accessed 5 January 2016.
Hodel, D. R. 1988. Exceptional Trees of Los Angeles. California Arboretum Foundation, Arcadia.
Powell, M. H. and S. B. Westley. 1993. Erythrina Production and Use: A Field Manual. Nitrogen Fixing Tree Association, Paia, HI.
Raven, P. H. 1974. Erythrina (Fabaceae): achievements and opportunities. Lloydia 35: 321-331.
Sourakov, S. 2011. Niche-partitioning, co-evolution and life histories of erythrina moths, Terastia meticulosalis and Agathodes designalis (Lepidoptera: Crambidae). Trop. Lepid. Res. 21(2): 89-94.
Sourakov, A. 2012. On the biology of moths that feed on Erythrina in Florida. Trop. Lepid. Res. 22(2): 110-118.
Sourakov, A. 2013. Erythrina moths Terastia meticulosalis Guenée and Agathodes designalis Guenée. Department of Entomology, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Publ. EENY 516. Available on- line: http://edis.ifas.ufl.edu/in921.
Sourakov, A., D. Plotkin, A. Y. Kawahara, L. Xiao, W. Hallswachs, and D. Janzen. 2015. On the taxonomy of the erythrina moths Agathodes and Terastia (Crambidae: Spilomelinae): Two different patterns of haplotype divergence and a new species of Terastia. Trop. Lepid. Res. 25(2): 80-97.
Swezey, O. H. 1923. The Erythrina twig borer (Terastia meticulosalis) in Hawaii (Pyralidae, Lepidoptera. Proc. Hawaiian Ent. Soc. 5(2): 297-298.
Zimmerman, E. L. 1958. Insects of Hawaii. Vol. 8 (Lepidoptera: Pyraloidea). University of Hawaii Press, Honolulu.
Donald R. Hodel is landscape horticulture advisor for the University of California Cooperative Extension in Los Angeles. email@example.com.
James E. Henrich is curator of living collections at the Los Angeles County Arboretum & Botanic Garden in Arcadia, CA. firstname.lastname@example.org.
Kenneth J. Greby is an arborist with ArborPro in Yorba Linda, CA. email@example.com.
Gevork Arakelian is the entomologist with the Los Angeles County Agricultural Commissioner/ Weights & Measures in South Gate, CA. GArakelian@acwm.lacounty.gov.
Linda M. Ohara is a biology sciences lab technician at El Camino College in Torrance, CA, a horticulturist, and a former nurserywoman. firstname.lastname@example.org.
Surendra K. Dara is Strawberry and Vegetable Crops Advisor and Affiliated IPM Advisor for the University of California Cooperative Extension, San Luis Obispo, Santa Barbara, and Ventura Counties, email@example.com.
This article is a reprint of the original article published in the eJournal, PalmArbor.
- Author: Cheryl Reynolds
- Author: Petr Kosina
Whether or not your favorite team is playing in Sunday's big game, the Super Bowl is often a great excuse to gather with friends and family and enjoy some tasty treats! Maybe your favorite snack involves chips with salsa or guacamole, or perhaps you prefer shrimp with a delicious avocado dip. Whatever your snack of choice, chances are that you might spice it up with a little cilantro or parsley.
Cilantro and parsley growers have something else to be happy about – The UC Statewide IPM Program just released new Pest Management Guidelines for Cilantro and Parsley.
Cilantro and parsley are herbs used both fresh and dry for preparation of many popular dishes in almost all parts of the world including California. Apart from their pleasant flavor, both plants are also known for a number of nutritional and health benefits.
In California, cilantro and parsley are grown commercially on more than 7,000 acres, primarily along the southern and central coast. Cilantro (also known as Chinese or Mexican parsley) and parsley are examples of specialty vegetable crops important in crop rotations and in contributing to California's overall agricultural diversity.
Although pest problems aren't too common for home gardeners growing cilantro or parsley, for commercial growers, crop damage due to insect pests and diseases may be devastating and cause important economic losses. The new UC IPM Pest Management Guidelines for cilantro and parsley provide pest and management information for insects pests (including beet armyworm, cabbage looper, and aphids), diseases (including apium virus Y, bacterial leaf spot, carrot motley dwarf, cilantro yellow blotch, Fusarium wilt, and septoria leaf spot), and nematodes. Because weed management costs can be very high in cilantro and parsley unless weed control programs are carefully planned and implemented, a comprehensive weed management section is also included.
Check out the new guidelines and other pest management information on the UC IPM website.
- Author: Cheryl Reynolds
Are you looking for continuing education units (CEUs) to complete your renewal application this year for the Department of Pesticide Regulation (DPR)? The UC Statewide IPM Program has several online courses available that can help you get those last few needed credits.
DPR license and certificate holders with last names beginning with M – Z renew this year. Renewal packets must be submitted to DPR before November 19th to ensure that licenses are renewed by January 1, 2016. After that, applications may take up to 45 calendar days to process.
The online courses available from UC IPM that offer units for DPR license renewal include:
- Providing Integrated Pest Management Services in Schools and Child Care Settings (1 unit Laws and Regulations and 1 unit Other)
- Pesticide Resistance (2 units Other)
- Pesticide Application Equipment and Calibration (1.5 units Other)
- IPM – A Solution for Reducing Pesticides/Water Quality: Pesticide Properties (1 unit Other)
- The Impact of Pesticides on Water Quality/Mitigating Urban Pesticide Runoff (1 unit Other)
- Water Quality and Mitigation: Bifenthrin and Fipronil (1 unit Other)
- Herbicides and Water Quality (1 unit Other)
CEUs from the Structural Pest Control Board are also available for most of these courses.
For a list of other approved online or in-person courses, visit the DPR website. UC IPM plans to add additional online courses for 2016, including those available for Laws and Regulations units. For more information about the courses UC IPM offers as well as additional training opportunities and pest management information, see the UC IPM web site.
- Author: Surendra K. Dara
San Diego County entomologist, Tracy Ellis recently reported the occurrence of a small gall midge in Rancho Santa Fe and La Jolla. Established populations of the ficus eye-spot midge, Horidiplosis ficifolii Harris & de Goffau 2003 (Diptera: Cecidomyiidae) were found in Indian laurel fig (Ficus microcarpa var. nitida) in late 2014. Early last year, another exotic pest, weeping fig thrips (Gynaikothrips uzeli) was found infesting weeping fig (F. benjamina).
Origin and Distribution: Eye-spot midge is native to South East Asia. It was first described from the infestations in weeping fig imported from Taiwan to the Netherlands which later moved to UK. Galls collected in UK and larvae and adults reared in Denmark and the Netherlands were used to describe the pest. Eye-spot midge was later reported in Italy in 2007, USA (Florida) in 2008, and the Czech Republic in 2010.
Host range: It appears to be a primary pest of ornamental figs hence the specific name ficicolii which means 'of fig leaves'. In California, Florida and the Czech Republic, eye-spot midge was found on the Indian laurel fig, in Denmark, UK, and the Netherlands on the weeping fig, and in Italy on a host referred to as ornamental fig.
Damage: Larvae form galls on young leaves. Galls are irregularly shaped and about 4 mm in diameter. When larvae exit the galls for pupation, galls collapse and become dark brown, sunken spots that could be mistaken for leaf spots caused by bacterial or fungal diseases. Circular exit holes of 1-2 mm diameter can be seen on older galls. Heavy infestations could lead to leaf fall.
Biology: Information on eggs is lacking, but they are probably deposited on foliage. Young larvae are translucent and about 1 mm long. They make galls and develop individually inside each gall. Mature larvae are bright orange and up to 2 mm long. Mature larva exits the galls to pupae in the soil or other substrates. Adults are small midges with brownish orange bodies and are weak fliers. Wings do not have any markings and are 1.6 mm long in males and 2 mm in females. Life cycle is completed in about one month at 20oC or 68oF.
Management: There are no specific management options reported in any literature except for the removal and destruction of the infested foliage.
What to do: If you suspect ficus eye-spot midge infestations, please inform your local Ag Commissioner or University of California Cooperative Extension office.
Beránek J. and I. Šafránková I. 2010. First Record of Horidiplosis ficifolii Harris 2003 (Diptera: Cecidomyiidae) in the Czech Republic. Plant Protect. Sci. 46: 189–191.
Caldwell. D. 2012. Ficus trees under attack! https://palmbeachcountyextension.files.wordpress.com/2012/01/ficus-trees-under-attack.pdf
Harris K.M. and L.J.W. De Goffau. 2003. Horidiplosis ficifolii, a new species of gall midge (Diptera: Cecidomyiidae) damaging ornamental fig plants, Ficus benjamina L. Tijdschr. Ent. 146: 301–306.
Steck G.J. and S. Krueger. 2008. An ornamental fig pest, Horidiplosis ficifolii Harris (Diptera: Cecidomyiidae), genus and species new to Florida and North America. http://www.freshfromflorida.com/Divisions-Offices/Plant-Industry/Plant-Industry-Publications/Pest-Alerts/Pest-Alerts-An-Ornamental-Fig-Pest-Horidiplosis-Ficifolii-Harris-Diptera-Cecidomyiidae
Suma P., A. Russo A. and S. Longo. 2007. Horidiplosis ficifolii (Diptera Cecidomyiidae) infestante su Ficus ornamentali in Sicilia. In: Proceeding XXI Congresso nazionale italiano di Entomologia, Catania 10–15 Giugno: 230.
Taxonomic description on Fauna Europaea http://www.faunaeur.org/full_results.php?id=303211
van der Gaag, D. J., E. Dijkstra, W. Lammers, A. Meijer, and E. J. Scholte. 2006. Pest risk analysis: Horidiplosis ficifolii Harris. https://www.nvwa.nl/txmpub/files/?p_file_id=2000933/span>