Persimmon Pest Management in the San Joaquin Valley By Devin Carroll Revised 2013

Transcription

1 Persimmon Pest Management in the San Joaquin Valley By Devin Carroll Revised 2013 Persimmon is a minor crop in California, and so far it has no University of California pest management manual or website section in the UC IPM Project. UC IPM does have some information in the ornamentals section. UC Division of Agricultural Science has a 1982 leaflet, Growing Persimmons, but so far I have not located a copy to read. 6 In this paper I summarize what I have learned during several years of monitoring some blocks of Fuyu and Hachiya persimmons near Earlimart, and one young block of Fuyu persimmons near Reedley. I will cover only arthropod pests. Most of the pests I have seen on persimmon are also pests of pistachio, so the information in the pistachio section of the UC IPM Project is very useful. 8 The list of insecticides registered on persimmons is very short. Conventional insecticides include various brands of imidacloprid and the miticide Apollo (Omite and Acramite can be used non-bearing). Recently the Movento label added persimmon, and Nichino expects to register Applaud in Soft chemicals include pyrethrin, some neem products (azadirachtin), specialty oils (Ecotrol) and Bacillus thuringiensis (B.t.). Lepidoptera UC IPM lists fall webworm (Hyphantria cunea) and redhumped caterpillar (Schizura concinna) as pests of ornamental persimmons. 7 So far I have not seen them. New Zealand authorities report light-brown apple moth (Epiphyas postvittana), as a pest of persimmons. 2 LBAM is now present and spreading in California, and persimmon growers should watch for it. LBAM is a leafroller similar to oblique-banded leafroller (OBLR, see below). Quarantine may be its principle economic hazard. In the south Atlantic states the persimmon borer, Sannina uroceriformis, a clearwinged moth (Sesiidae), is a pest of American persimmon. The larva may bore seventeen to twenty-two inches below the surface of the ground or in the trunks aboveground. 3

2 One persimmon grower informed me that Mexican authorities identified OBLR in shipments of his persimmons, which were then rejected because of their quarantine. I have not found literature references to OBLR in persimmon. I have seen leafroller damage, but so far I have not identified any worms. I presume that the damage is caused by OBLR, but possibly some other tortricid worm such as omnivorous leafroller (OLR) could be involved. Treatment timed for OBLR seems to help. Oblique-Banded Leafroller (OBLR) Choristoneura rosaceana OBLR is a large leafroller that feeds in a silk nest, usually underneath the calyx or under an old flower stuck to the fruit. Typically, the calyx is damaged more than the fruit, but calyx damage may result in a cull even if the fruit itself is unmarred. Under old flowers the fruit skin is more often damaged. Also, OBLR worms are forbidden in shipments to Mexico, which is a major importer. OBLR damage to calyx. OBLR has three generations in the San Joaquin Valley. 8 Second instar worms overwinter under bark. They emerge in late March or early April to begin feeding on leaves. This approximately coincides with pistachio bloom, and is an effective timing for B.t. sprays. This Fuyu flower has persisted on the fruit, providing protection for OBLR feeding underneath. Treatment of the second and third generations can be timed using pheromone trap biofixes and degree days. UC IPM Online has a degree day Flower removed showing damage.

3 model. Traps should be placed by mid-april (Kern, Tulare, and Kings Counties), or April 25 (Fresno and north). I usually catch 1-2 OBLR moths per month, but every week I find hundreds of the garden tortrix, Ptycholoma peritana, a much smaller moth, about the size of an OLR, which breeds in weeds. OBLR biofixes and degree day updates for Fresno and Tulare counties are available from Sticky Notes, maintained by Kelley Morrow, at I have not seen OBLR damage a high percentage of persimmon fruit, even when untreated. 1-2% damage can occur. I usually treat the first generation with B.t., and often the second generation. Treatment of the second and third generations is hampered by the difficulty of reaching the larvae hiding under the calyxes. Mealybugs UC IPM lists Comstock (Pseudococcus comstocki), Gill s, and longtailed mealybugs on ornamental persimmons. 7 I am confident that I commonly see grape mealybug. Recently John Hubbard of Nichino has seen long-tailed mealybug causing problems on persimmons near Reedley. I have not seen Comstock mealybugs. In my opinion the best available materials for all these materials will probably be Movento and Applaud, timed for the crawlers in early to mid-june. Gill s Mealybug Ferrisia gilli Gill s mealybug, sometimes called striped mealybug, is by far the most damaging pest of persimmons when it occurs unchecked by natural enemies. Hundreds of mealybugs will cluster on each fruit, and in the worst areas, 100% of the fruit can be Long thin wax filaments characterize Gill s mealybugs.

4 ruined. Gill s mealybug can be distinguished from grape and other mealybugs by its long hair-like wax filaments from the dorsum. Gill s mealybug produces live crawlers without an egg stage. On pistachios, it has three generations per year. 8 Based on my observations in persimmons around Earlimart, it appears that the three generations might be maturing a little earlier on persimmons than on pistachios. Females mature in late fall and produce crawlers that overwinter in hidden spots on the trunk. 8 At budbreak in pistachios the crawlers begin feeding on the new buds, and they mature around the end of May. In persimmons in 2010, I first noticed half-grown crawlers at the end of March, and they matured at the end of April. Most of these adults moved to the trunks. They began producing first generation crawlers by May 13. The crawlers migrated to the leaves. They matured starting in early July, and moved off the leaves to nearby woody branches. Many began finding fruit at this time. This compares to maturity in mid-july in pistachios. 8 Second generation crawlers appeared in the persimmons by July 14. Many congregated on fruit, especially around the calyx, or where two fruit touched, or at the tip of the fruit. These mealybugs matured near late August, compared to mid-september in pistachios. 8 Third generation crawlers appeared in persimmons by September 8. This is the overwintering generation, which moves off the fruit back to the trunk. The best time for chemical control of Gill s mealybug is late May to early June, when most are small crawlers on the leaves. By early July and afterwards, too many are hidden under calyxes or between fruit. Movento might work even in areas protected from direct spray. We tried Aza-Direct at 32 oz. with 5 oz. Nu-Film 17 in 150 gallons water, but not many mealybugs died. Perhaps a higher rate or better coverage would be more successful. Imidacloprid works moderately well, but it has not tested well compared to Applaud or other choices, and it is harmful to parasites and predators (pers. comm. David Haviland, and my observations in grapes). I suspect that use of imidacloprid to control soft scales in lead to the severe mealybug problems I observed in In some instances, infestations of Gill s mealybug in persimmons have disappeared before causing much damage (Haviland). Presumably natural enemies Parasitized mummy. achieved this control. Natural enemies also control Gill s mealybugs in almonds (Haviland). In some sections of the Earlimart persimmons in 2010, I found

5 evidence that these predators and parasites were providing adequate control. But in other sections, the population reached very damaging levels. In the population decreased to cause only spotty moderate damage, without any treatment. The only parasite I have seen is Anagyrus pseudococci. Other parasites known to attack Gill s mealybug include Pseudaphycus sp. and Chysoplatycerus sp. 8 I found only 1-10% parasitism in the heavier Gill s infestations, but this parasite probably is a key to control where populations are low and at the end of the season. Brown lacewings are known predators, but I did not notice any. Green lacewings contributed significant predation. The predaceous gall midge, Dicrodiplosis californica, often feeds on mealybugs massed under calyxes. This midge is a key to control of grape mealybugs in vineyards. The lady beetle Nephus sordidus or little brown mealybug destroyer may also be an important Gill s predator. The larvae have waxy coverings that make them resemble mealybugs. Grape Mealybug Pseudococcus maritimus Grape mealybug (GMB) can be a significant pest of persimmons, but not nearly as bad as Gill s mealybug. GMB has two long waxy tails. The generational history of GMB on persimmon is similar to that on grapes. Egg masses overwinter, sometimes with crawlers hatched. They finish hatching in late February and move out to the buds and leaves. As they near maturity they move back to the trunk, where they produce egg masses starting in mid-may. New crawlers hatch beginning in early June, and by the end of June most have moved out to the fruit and leaves. This second generation matures beginning in late July. Some may create egg masses on the fruit under calyxes, but the majority returns again to the bark. Most are gone from the fruit before harvest. Predaceous gall midge maggot with grape Mid to late June is a good time for mealybugs on grape pedicel. chemical control. Late March might also be good. We also had fair success with 25 oz. Aza-Direct, with 5 oz. Nu-Film 17 in 150 gallons water, applied June

6 28 in I found many dead bodies, and by July 14 I could find only a few exposed that were alive. However, there was a fair number hidden under calyxes. GMB has good biological control in persimmons. I suspect that the trouble we had in 2008 was partially caused by two years of applying imidacloprid to control soft scales. Natural enemies are the same as in grapes: predaceous midges, the little brown mealybug destroyer, lacewings, and parasites in the family Encyrtidae. Longtailed mealybug Pseudococcus longispinus This information is gleaned from UCIPM sections on avocado and citrus and from correspondence with John Hubbard of Nichino America, who has observed this species at serious levels in persimmons near Reedley. Longtailed mealybug is distinguished by extremely long wax tails. In citrus and avocado, this species has 2-4 overlapping generations a year. It is typically controlled by natural enemies including the usual predators and the parasites Acerophagus notativentris, Arhopoideus peregrinus, and Female long-tailed mealybug. Photo by David Rosen from UCIPM. Anarhopus sydneyensis. A. notativentris is also the most common parasite of grape mealybug. In persimmons, the life cycle is similar to Gill s mealybug (Hubbard). The generations may be more distinct than in citrus and avocado. Females give birth to live young and crawlers can be seen emerging in the first two weeks of June. This should be good timing for Applaud or Movento and coincides with timing for other mealybugs and soft scales. Another generation of crawlers emerges beginning in August and continues for several weeks into September. In both generations they can be found on the scaffold branches, the leaves and the fruit, especially under the sepals. They produce copious amounts of honeydew on the fruit, leading to black sooty mold which makes the fruit unpackable.

7 Armored Scale Insects UCIPM lists greedy scale (Hemiberlesia rapax) as a pest of ornamental persimmons. 7 Eberling states that latania scale (Hemiberlesia lataniae) is sometimes seen, especially under the sepals of the fruits 3. I occasionally see Hemiberlesia, but they have never been serious. Hemiberlesia scale on green fruit. Soft Scale Insects UCIPM lists European fruit lecanium scale as a pest of ornamental persimmons. 7 This scale is very common in persimmon orchards. I also often see the closely related frosted scale. I have seen brown soft scale on one a couple of occasions. Eberling also mentions black scale (Saissetia oleae) on persimmon. 3 European fruit lecanium scale Parthenolecanium corni Frosted scale Parthenolecanium pruinosum These two soft scales look very similar, and have identical life histories, so they can be treated as one pest, Parthenolecanium. They damage fruit Lecanium scale egg sacs on twig. by depositing honeydew which fosters black sooty mold. On some hosts such as pistachios, Parthenolecanium reportedly has one generation per year, but on grapes and persimmons in the San Joaquin Valley there are two generations. They overwinter partially grown, and begin reaching maturity as egg sacs in late March or early April. The first eggs typically hatch during the first two weeks of May, and most of the new crawlers move to leaves. Early June, when all are hatched

8 and the majority is exposed, is the best spray timing. Most of the honeydew is produced by the larger instars during the last half of June and early July. Second generation egg sacs begin to appear near the end of June, and the eggs begin hatching some time in July, producing the crawlers that will eventually overwinter. Parasites are capable of maintaining Parthenolecanium populations at acceptable levels. Presumably the parasites are the same as in grape: Coccophagus scutellans, which Frosted scale near maturity. attacks small stages of scale, C. lycmnia, found in second and third stage scale, and Metaphycus luteolus, with multiple adult emergences from third state scale (pers. comm. Kent Daane). The parasites can be disrupted by ants or pesticides, leading to more serious damage. Applaud, when it gets registered, should work very well in an early June application. Imidacloprid is reasonably effective, but is disruptive to parasites of both soft scales and mealybugs. Movento has not tested well on soft scales in other crops. Brown soft scale Coccus hesperidum I occasionally see a few brown soft scale in persimmons. In citrus and pomegranates this scale is potentially a serious pest but is usually controlled by parasites. It has multiple overlapping generations. A June timing with Applaud, when it is registered, should provide control. Brown soft scale: Near maturity on a twig (above); Nymph on a sepal (below).

9 White Flies California Rare Fruit Growers mention whiteflies on persimmon. 1 I have not seen them. They could be controlled by Movento or by Applaud when it is registered. Beetles UCIPM lists flatheaded borers (Buprestidae) and Fuller rose beetle (Asynonychus godmani) as pests of ornamental persimmons. 7 I have not seen them in orchards. In Eastern United States the twig girdler, Oncideres cingulata, is an important pest of the indigenous American persimmon. 3 The flatheaded appletree borer, Chrysobothris femorata, mainly attacks young trees unprotected from sunburn. 3 Thrips California Rare Fruit Growers mention that thrips can cause skin blemishes on fruit. 1 I have not seen them. Mites The persimmon bud mite (Aceria biopsidia) causes a condition known as brown lace collar. 7 This species occurs under fruit buttons and under buds scales on cultivated persimmon in southern California. Mites blacken the fruit surface and stem under fruit buttons, and evidently are implicated in premature dropping of fruit. 4 This mite is presumably the reason that several miticides are registered in persimmons. Japanese researchers report that bud mites hibernate inside dormant buds and become active in March. After budbreak, they stay under the bud scales until the end of April. In May, they move to leaves, mainly next to midribs where trichomes provide cover. Some also enter axillary buds where they remain until winter. After petal fall, bud mites infest fruit under the calyx. Peak infestation is in middle to late July. The best time to spray in Japan is in May. 5 So far I have not seen brown lace collar in the San Joaquin Valley.

10 References 1. California Rare Fruit Growers Persimmon Fruit Facts Dentener, Peter R., Philip J. Lester and Allan B. Woolf A report on effective disinfestation of persimmon pests while reducing chilling injury. Persimmon Profile, Journal of the Persimmon Industry Council, December 1995 pg Ebeling, Walter Subtropical Fruit Pests. Univ. Calif. Div. Agric. Sci. 4. Jeppson, L. R., H. H. Keifer, and E. W. Baker Mites Injurious to Economic Plants. Univ. Calif. Press. 5. Katsumi, H., & I. Katsunori Biology of the persimmon bud mite (Aceria diospyri Keifer) and its control by pesticides. Bull. Yamaguchi Agri. Exp. St. 53: LaRue, J.H., K.W. Opitz, and J.A. Beutel Growing Persimmons. Univ. Calif. Div. Agric. Sci. Leaflet UC IPM Online. How to manage pests in gardens and landscapes: persimmons UC IPM Online. Pistachios.