Barnett, William W. : William W. Barnett is Area IPM Specialist, Fresno County

Bentley, Walter Joseph

Flaherty, Donald L. : Donald L. Flaherty, Farm Advisors in Tulare and Kern counties

Jones, Richard A

Rice, Richard

Monitoring and modeling oriental fruit moth in California Richard E . Rice 0 William W . Barnett 0 Donald L . Flaherty J . Bentley 0 Richard A . Jones Walter 20to 30acres ; one trap per each 10 acres for I - C trap . These traps consist of a wire frame oriental fruit moth , Grapholitha molesta 30 to 80 acres ; and one trap per each 20acres a plastic - coated cardboard top , and hanger , ( Busck ) , has been an important pest of in orchards larger than 80 acres . Oriental and peaches and nectarinesin California sincethe a cardboard bottom coated on the inner fruit moth pheromone traps used in thisman - mid - 1950s . It is also an occasional pest of A rubber cap surface with adhesive material . ner will produce typical seasonal collection impregnated with the OFM pheromone is other stone and pome fruits and quince . In 1 . data similar to those in figure placed within the trap on the sticky bottom . 1972 , development of a sex pheromone trap Traps should be checked and serviced twice Traps should normally be placed in for oriental fruit moth ( OFM ) led to in - or - weekly , and three times per week during creased efforts to monitor OFM populations chards by March 1to collect the first emerged critical flight periods ( early March and early so that timing of sprays to control the insect of the season . These early collec - male moths May ) . In most commercial orchards , trap tions are important in later use of the OFM could be improved . The following report bottoms ( liners ) are replaced at four - week in - briefly describes suggested standard OFM phenology model . The traps should be posi - 250to 300 moths have accum - tervals or when 6 to 7 feet high on the north or east tioned trapping techniques . Also discussed is use of ulated and have been removed from a liner side of the tree , a simplified phenology model ( showing the 1 to 3 feet inside the dripline . over a period of time . The OFM pheromone relation between climate and the insect's bio - At least two , and preferably three , traps dispenser ( rubber cap ) should also be re - logy ) in conjunction with pheromone trap or varietal should alwaysbe used per orchard placed every four to six weeks . data in making decisions for management of block , regardless of how smallthe size . Single traps often produce inaccurate data . Sug - Using seasonal collection and temperature OFM . for different 1972 gested optimum trap densities data from California and Michigan for The most efficient trap presently available through 1978 , entomologists at Michigan acreages are : one trap per each for monitoring OFM is Zoecon's Pherocon 5 acres , up to State University were able to develop a fairly simple phenology model for OFM . The ( DO ) values for threshold and day - degree OFM life stages used in this model are shown 1 . in table In 1979 , six peach and nectarine orchards in the central San Joaquin Valley were moni - tored for OFM , and Dovalues for each flight TABLE 1 . Threshold and ( DO ) values used in the day - degree oriental fruit moth phenology model OFMdevelopment Dovalues Lower threshold 45 " F Upper threshold 90 " F : 50 Do Pre - ovipositionfemale 143 Do Egg First moth to egg hatch : 193 Do Larval development : 387 Do Pupal development : 283 Do Average generation : 963 2 46 Do ' The lower threshold is the temperature below which the in - sect's development stops ; the upper threshold the temper - ature above which the development rate begins to decrease . of heat between the two thresholds that is need - The amount to develop from one stage to the next is ed for the insect calculated in day.degrees - the degrees of temperature above a threshold for each day . CALIFORNIA AGRICULTURE , JANUARY - FEBRUARY 1982 11 during the season were calculated using the an The following hypothetical situation is 45 " and 90 " F thresholds ( see table 2 ) . The example of how the OFM model could be put observed OFM flights and calculated Do to commercial use . We know that oriental values agree fairly well with the expected Do fruit moth requires approximately 200 Do for a generation . The data in table 2 also from the time the first moths are collected in show a tendency for the Dovalues to become pheromone traps in any given generation un - somewhat greater with each successive til the first eggs begin to hatch in that same Do generation . This shift toward higher generation ( table 1 ) . At the same time we values is thought to be caused by hotter tem - know that first egg hatch is generally too early peratures in mid - summer , but is not of as optimum timing for control of hatch - to use enough concern to invalidate the model . ing larvae in that generation . Therefore , Another method of comparing observed rather than timing chemical control treat - OFM flights and calculated Dovalues per D " ) , ments at the beginning of egg hatch ( 200 generation is shown in figure 2 . These data , we could begin treatment after an additional taken from an untreated mixed block of 200 Dointo the generation ( fig . 2 ) . The total stone fruits at Parlier , show the accumulated of 400Dofrom first moth would put the time Do between the first moths collected on of treatment closer to the observed or ex - March 5 , and the first moths of each succeed - pected moth flight peak ( current standard 8 / 24 ) . When ing flight ( 5 / 10,6 / 15,7 / 22 , and practice ) , and also when first - hatched larvae Oriental fruit moth adult . the Dovalues are thus plotted along with the or early are in approximately the late second moth flight curves , a better understanding of third instar stage . Using these criteria , timing the accuracy of the OFM phenology model OFM larvae , and foliar sprays in March and of chemicaltreatments in the first moth flight can be gained . April have been difficult to time properly be - ( March - April ) or the preferred second flight of inclement weather patterns . The After development of this model , the next cause of ( May - June ) should provide good control standard approach to OFM control over the step is to find ways to use it to advantage in OFM larvae . years has been to treat the second flight and OFM management programs , particularly in of treating specific genera - This concept relationto the timing of chemicaltreatments . larval hatch in May , followed by additional tions based on accumulated D " followingob - treatments as necessary on later flights . Dormant sprays do not affect overwintering served first moth flight and egg hatch has yet to be fully tested under field conditions . But comparisons of these Do values , superim - posed upon prior years ' observed moth flights , at least provides a point at which to begin evaluating such chemical treatments . As future modelsare developed , somedata gaps will need to be addressed . In particular , additional data are needed on the effect of ( 95 O to 110 " F ) summertemperatures on high OFM egg and larvaldevelopment.The model an upper threshold value of presently uses 90 " F , but it is believed that the hot summer temperatures ( above90 " F ) in the San Joaquin Valley may suppress egg and larval develop - ment . This effect would tend to extend the observed generation time for oriental fruit moth into 1100 to 1200 Doaccumulated val - ues rather than the expected values of about 920 to 1010 Do.However , in spite of this ap - parent late - season deficiency in the present model , the consensusis that it is still valid and can be used for many field applications . Richard E . Rice , Entomologist , Department of Entomology , Davis , is located at the Universityof California San Joaquin Valley Research and Extension Center , Parlier ; William W . Barnett is Area IPM Specialist , Fresno County ; Donald L . Flaherty and WalterJ . Bentley are Farm Advisors in Tulare and Kern counties , respectively ; and A . Jones , Staff Research Associate IV , Richard Department of Entomology , Davk , is located at Parker , This research was supported by grants from the CaliforniaTree Fruit Agreement . 12 CALIFORNIA AGRICULTURE , JANUARY - FEBRUARY 1982