Serpentine Leaf Miner Damage by linzhengnd


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3erpentine leaf Miner Damage
         spinach losses in 1956 recall cyclic attacks by pests and
         need of both insecticides and natural enemies for control
                                                                                            W. H. Lange, A. A. Grigarick, a n d E. C. Carlron

A small leaf-mining agromyzid fly of                                                                  On some host plants, and when several
omnivorous tastes-Liriomyza          langei                                                        larvae work in the same leaf, blotch
Frick-caused a 50% loss to fall spinach                                                            mines develop, and entire leaves turn
in the Salinas Valley in 1956. The unof-                                                           white and wither. Mining may occur in
ficial allowable tolerance for larvae could                                                        the pods of peas, and stem mining may
not be met i n many instances with as                                                              cause the complete collapse of small
many as six weekly applications of com-                                                            plants.
bination phosphate and chlorinated hy-                                                                The mature larva, when 2 nini to 4 inm
drocarbon insecticides at a total cost of                                                          lonq, cuts an escape slit at the end of
$60 an acre.                                                                                       the mine and pupates on the leaf-in
   Widespread leaf miner attacks appear                                                            certain species as in Liriomyza picteih-
to be cyclic in nature, although localized                                                         or at the base of the plants. or in the soil,
attacks by certain species occur prac-                                                             as in L. langei.
tically every year. Evidence indicates a                                                              The period of development varies with
flareup about 1938, one in 1948, and a                                                             species, host, and time of year. A typical
more limited epidemic in 1956. In 1945                                                             life history consumes from 17 to 30 days
                                              Mines of the pea leaf miner on l e a f - a b o v b   in the summer and 50 to 65 days in the
a 10-acre field of spinach at Salinas was             and on pad-below--sf pea.
lost because of a localized attack.                                                                winter and spring. There are five to six
   Leaf miners are                                                                                                       generations a year in
subject to explosive                                                                                                     most species, and all
population buildups                                                                                                      stages may overwin-
-biological       explo-                                                                                                 ter, but largely as
sions-as       there is                                                                                                  pupae and adults.
often a delicate bal-                                                                                                    Adults may start
ance between cli-                                                                                                        feeding on new
m a t i c influences,                                                                                                    growth in January
parasites, available                                                                                                     and February. Pop-
hosts, and the repro-                                                                                                    ulations of flies usu-
ductive potential of the leaf miners.         Below-Feeding    puncturer and miner of pea leaf
                                                                                                   ally increase as summer and fall progress
   Climate exerts an important over-all                       miner on spinach.                    and more available hosts are present.
effect in determining the abundance of                                                                The most important species of serpen-
leaf miners. Favorable conditions OC-                                                              tine leaf miners attacking spinach in the
curred in the Salinas Valley in 1956.                                                              coastal districts is the pea leaf miner-
   Winding mines inside the leaves, stems                                                          Liriomyza langei Frick-which has been
-or      pods-of    the plant attacked are                                                         called L. flaueola Fallen or L. orbona
characteristic of serpentine leaf miners                                                            (Meig.) .
and caused by boring larvae.                                                                          Other species attacking spinach are
   The adult serpentine leaf miners are                                                            the bean leaf miner-L. pictella (Thom-
small, black and yellow flies ranging                                                              son) -which has been called L. subpu-
from 1/1,,” to % 6 ” long. The members                                                             s i b Frost, a valley species; Phytomyza
of the genus Lirzomyza-which contains                                                              atricornis Meigen-which mines spinach,
most of the agriculturally important                                                               lettuce, and composites in the Salinas
species-have a yellow mark on the pos-                                                             and other areas; and the spinach leaf
terior part of the thorax between the                                                              miner-Pegomyia hyoscyami (Panz.) -
places of attachment of the wings. The                                                             which forms large blotch mines and has
adult females puncture holes in the leaves                                                         mature larvae %’’ long.
for feeding and for egg deposition. Many                                                              Other economic species include the
more feeding than egg punctures usually                                                            cabbage leaf miner-Liriomyzu           bras-
occur. The punctures turn light-colored                                                            sicae (Riley) ; the tomato leaf miner-
and give the leaves a white, stippled ap-                                                          L. munda Frick (mss.) ; a grass leaf
pearance. Eggs are placed under the                                                                miner-L. flaueola (Fall.) ; and a miner
epidermis of the leaf through slits made                                                           of alfalfa and other legumes-L.         con-
on the upper or lower surfaces of the                                                              gesta (Becker) . A miner of cabbage in
leaves. The slits are ovate in shape, range                                                        northern California is Scaptomyza ter-
from 0.25 to 0.35 millimeter-mm-                                                                   minalis (Lowe). Two miners of weeds
long, and are laid parallel to the leaves.                                                         are often confused with Liriomyza: Ha-
The diameter of the mine increases as the                                                          plomyza minutu (Frost), a miner of
larva grows.                                                                                                    Continued on next page

C A L I F O R N I A A C R I C U L T U RE, M A R C H , 1 9 5 7                                                                                 9
               LEAF MINER                         nia was widespread 011 spinach, melons,         n?oving into the fields from outsicle. odd-
         Continued from preceding page
                                                  tomatoes, alfalfa, lettuce, sugar beets.        itig to those escaping destruction.
                                                  cultivated flowers, potato, beans, weeds.          The best solution to the leaf miner
Chenopodiurn spp.; and H. togata ( Me-            black-eyed peas, and mustard. An attack         control problem seems to lie in the judi-
lander ) , a common miner of Arnararithus         of Liriomyza larigei occurred on sugar          cious use of insecticides in such a way
SPP.                                              beets in the Salinas Valley in 1948, sup-       as to more fully utilize the natural ene-
  The pea leaf miner has a history of             posedly correlated with the widespread          mies.
damage to spinach. peas, peppers, lettuce,        use of DDT for leafhopper control.                 The most effective wasp parasites of
carrots. onions. cruciferous crops, asters.       Spinach. lettuce, and onions were at-           the pea leaf miner are Solerroius irrler-
sugar beets, celery, and beans. Cage tests        tacked in 19.56.                                naedius ( Girault) ,S. begirri Ashmead),
have verified the following additional               Often. localized outbreaks can be cor-       larval parasites in the family Eulophidae,
hosts: cineraria. zinnia. stock. guayule,         related with parasite relationships. the        and Halticoptera aerrea (Walker I . a lar-
cabbage. Brussels sprouts, kohlrabi,              use of excessive amounts of insecticides
                                                  destructive to the natural enemies, and               Adult female of Liriomyza langei.
         Adult male of Liriomyza langei.          the availability of suitable host plants.

                                                   Puparium, above, and mature larva, below, of
                                                                 pea leaf miner.

                                                  I n one instance in the Salinas Valley, the
                                                  reduction of Liriornyia langei was the re-
                                                  sult of a maximum diurnal temperature           val parasite that emerges through the
cauliflower. turnip. broccoli, okra. pars-        of 105" F, an unusual temperature for           pupae. Other parasites include Mesora
nip, radish. dandelion, endive, chicory,          coastal conditions.                             sp,, and Opius sp.. and Chrysocharis
rutabagas. and tomato. Larkspur is not               Parasites often control leaf miner in-       airrsliei Crawford, and C. parksi Craw-
attacked. The pea variety Green Admiral           festations, but they can not be depended        ford. A combined parasitism of         to
is tolerant of attack because of its growth       upon-as seeins to be the case for cur-          90;: is not unusual.
habit, whereas the usual hamper types             rently used insecticides-to control niin-          The best chemical control program de-
of peas are severely damaged. Weeds               ers to a degree sufficient to meet existing     pends upon the species. crop. and local-
such as Cherropodimi and Arnararrthus             mnggot tolerances. tinder extremely high        ity, but certain insecticides have shown
are commonly selected.                            population levels the flies are continually               Continued on next page
   The bean leaf miner on the other hand
selects beans. melons, castor beans. cow-                        Damage of the pea leaf miner to leaves of sugar beets.
peas. and alfalfa, but it can occur on
spinach in certain valley areas.
   In 1948 leaf miner trouble in Califor-

    Mines of the tomato leaf miner in leaves of
                   tomato plont.

4                                                                           C A L I F O R N I A A G R I C U L T U R E , MARCH. 1951
                                              New Carnation Pests
                                                       bud mite and leaf miner found in
                                                       California may cause serious problems
                                                                                                                                   A. Earl Pritchard

                                                 Carriation bud mites are exceedingly
                                              tin) and they prefer to live within the
                                              new shoots. between the bases of the
                                              leaves and stem, and under the flower
                                              calyxes. Their presence in large numbers
                                              is detected by somewhat greasy. dis-
                                              torted, and stunted new growth.
                                                 Because of the secretive habits of the
                                              bud mite, it has been very difficult to
                                              control. Parathion, chlorobenzilate. and
                                              Kelthane have given good control of ex-
                                              posed mites. but repeated applications
                                              of these chemicals s e n e only to keep
                                              down mite populations.
   Leaf injury caused by the maggots of the
             carnation leaf miner.               I n recent experimental plots at Red-
                                              wood City, two new cheiiiicals have
Carnation growers in California-              shown greater protiiise for hud mite con-
constantl! coml)atirig spider mites.          trol. One of these is Diazinon and the
thrips and aphids. and occasional infes-      other is I'hostex. an experimental cheiiii-
tations of carnation bud moth or meal) -      cal.
bugs-base t h o new pests to fight.              Excellent kill was ohtained with wet-            Distorted terminal shoots iniured by the
   The carnation Iiud mite-Aceria pam-        talile powder of Iliazition applied at a                       carnation bud mite.

clian/hi Keifer-was first discovered i n      rate of three pounds of a 2.5'' niaterial
California in 1952. A suhsequerit collcc-     per 100 gallons of water and 25' emul-         The native home of this pest is not
tion from Mar) land constitutes the onl)      sifiable l'hostex used at a rate of one pint   known. hut it was first found in several
other known record of this pest i n the       per 100 gallons of water. The addition         nurseries in San Mateo County in 1956.
western hemisphere. I t is probable that      of four ounces of a comtiiercial spreader      The maggots of this tin). black and yel-
the mite as introduced from Europe.           to the Diaziiion spray caused a rather         low fl) tunnel within the leaves. niaking
   The original infestation was found in      even tlistrihution of the residue over the     serpentine mines. As far as is known.
Sarita Barhara County, and a state-u ide      leaves arid possibly enhanced the per-         at the present time. onl) carnations sene
sur\e! I)! the State Departinelit of Agri-    forinatice. I'hostex. when used as a 25:'      as a host.
culture shobced the pest to he present also   \%ettahle  powder at a rate of three poutids      A 2'' parathion dust has given good
in Los Angeles and Orange counties.           per 100 gallons of water, was inferior to      control of the adult flies as the) emerge.
Iluring 19.56. infested nurseries were        the other chemicals. No plant injury was       Applications are made at 10- to 14-day
found i n the Sari Francisco Ray area. in     incurred in these tests.                       inter\ als.
                                                                                             _ _ _ --
Alaineda. Santa Clara. and Sat1 Mateo            The other new carnation pest is the           A. Enrl I'ritchnrd is Associnte I'rolcssor of
counties                                      carnation leaf miner-Liriornyzz n. sp.         Entoniolog), 1 f n i t w s i t t o i (.olriornia, S e r 6 e l q .

no beneficial effect and usuall) a dele-      iwnts. sjsteinic materials. hits. and          and possihle chemical residue proldenis.
terious effect on parasites i n addition to   other controls needs investigating. How-       DDT or related materials should not lie
rather poor control of miners. Such iri-      ever. riiild atid warm fall atid winter con-   used. If dieldrin. aldrin, or heptachlor is
secticides include DDT. DDD. niethox) -       ditions tend to increase riuriibers of flies   used early, it should he coiiilined w i t h a
chlor. perthane. TEPP. rotetione, and         on all host plants. Sugar beets, weeds.        phosphate.
toxapheiie. DDT was found to affect the       and lettuce are sources of flies and para-        The use of more than two or three in-
larval parasites. Solenotus spp.. more        sites.                                         secticide applications is not usually cco-
than Halhoptera, due to differences in           Insecticides should not lie applied         nomically feasible, and-under high leaf
the hiolog) of these species. Other ma-       earl) in the growth of spinach, so as to       miner population coriditions-ma?         not
terials--parathion.    meth) I parathion.     allow parasites to get started on the first    allow the spinach to meet urioficial allow-
EPR, aldrin, dieldrin, heptachlor. en-        generation of leaf miners. Where flies are     able larval tolerances.
drin. isodrin. chlordane. and lead ar-        ahundant-and       insecticides are neces-
                                                                                               Ic'. H . Lrrnge is Associnte I'roiessor o i En-
senate-may or may not affect parasites.       sary-parathion      applied as a 2:; dust                                        Californin, I)ni-is.
                                                                                             tomology, l i n i t w s i t y C J ~
but are more effectke in controlling the      at 4.5 pounds per acre, or the equivalent
leaf niiner.                                  as a spray, at ahout the rosette stage.          A. A . Grignrick is Senior Laboratory Tech-
                                                                                             nicinn. Entomology, l l n i i w s i t y of Calijornin,
   More work is needed to determine the       is usually effective when followed t))         Dnois.
best use of insecticides and still preserve   one or two additional applications at i-         E. 0'. Cnrlson is Associate Specialist in En-
natural enemies. The use of seed treat-       10-day intervals, depending upon growth        tomology, 1/nit:arsity 0.i Cnliiornia, Ibis.

C A L I F O R K I A A C R I C U L T U R E, M A R C H , 1 9 5 7                                                                                              5

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