|
|
How to Manage Pests
UC Pest Management Guidelines
Cucurbits
Spider Mites
(Reviewed 11/05,
updated 6/08)
In this Guideline:
|
|
|
Examine
leaves with a hand lens for spider mites. Frequently, infestations include a mixture
of spider mite species. Adult mites are about 0.06 inch in length, have four
pairs of legs, are greenish to pink or cream colored, and have various sized
black spots on the body. Under warm conditions spider mites move rapidly within
the colony area. Spider mites have four stages of development: (1) the oval,
somewhat translucent egg;
(2) a six-legged
translucent immature stage; (3) an eight-legged
immature stage;
and (4) the eight-legged adult
stage.
A generation may pass in as few as 5 to 7 days in mid-summer, or in a month
during cool periods. Spider mites produce webbing that is often filled with
cast skins, dust, and other debris.
Mite feeding results in the destruction of chlorophyll; leaves
become pale, stippled, and in later stages of infestation dry up and die. Loss
of color is pronounced on the under surface of leaves before it becomes
apparent on the upper side. Light infestations can be tolerated, but when
heavy, can result in lowered yield and reduced quality of fruit.
Biological control is an important component of mite management.
Take measures to ensure the survival of predators and parasites.
Biological Control
Several predators play an important role in regulating spider mite
populations, including the western
predatory mite (Galendromus [Metaseiulus] occidentalis), sixspotted
thrips (Scolothrips sexmaculatus), western
flower thrips (Frankliniella occidentalis), lady
beetles (Stethorus sp.),minute pirate bug (Orius tristicolor), and lacewing larvae (Chrysoperla carnea). The western predatory mite is the same size as
spider mites but lacks spots and ranges in color from cream to amber red. It is
available commercially, but research has not been done on the effectiveness of
releasing these predators in cucurbits. Sixspotted thrips and western flower thrips
are also effective predators, but naturally occurring populations of these
insects generally do not develop to high enough levels that they can provide
significant control until damage has already taken place. Both species are
tiny, slender insects about 1 mm or less in length. Sixspotted thrips has three
dark spots on each forewing; western flower thrips ranges in color from clear
lemon yellow to dark brown. Monitor western predatory mites and the two species
of thrips to determine if they are present in the field and their relative
population density in comparison with pest mites.
Cultural Control
Minimize dust and encourage naturally occurring predators and
parasites by limiting chemical rates and the number of applications. Control field
bindweed growing in or at the edges of a cucurbit field. Good water management increases
plant tolerance to these pests. After runners are 14 inches long, natural
enemies such as sixspotted thrips or predaceous mites usually control pest mite
populations.
Organically Acceptable Methods
Biological and cultural controls and sulfur sprays (not for use on
sulfur sensitive varieties) are acceptable to use in an organically certified crop.
Monitoring and Treatment Decisions
No threshold is established, but when buildup is observed either
spot or completely treat the field before webbing occurs or before runners are
14 inches in length, providing no predatory thrips or predaceous mites are
present. After the rows close over, ground equipment cannot get in the field
and chemical treatment must be applied by aircraft. Such treatments are less
effective because it is difficult to obtain good coverage by aircraft.
| Common name |
Amount/Acre |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
|
| When choosing a pesticide, consider information relating
to water quality and impact on natural
enemies and honey bees.
|
| |
| A. |
BIFENAZATE |
| |
(Acramite) 50WS |
0.75–1 lb |
12 |
3 |
| |
MODE OF ACTION GROUP NUMBER1: 25 |
| |
| B. |
ABAMECTIN* |
| |
(AgriMek) 0.15EC |
8–16 fl oz |
12 |
7 |
| |
MODE OF ACTION GROUP NUMBER1: 6 |
| |
| C. |
DICOFOL |
| |
(Kelthane) 50 |
1.25 lb |
48 |
2 |
| |
MODE OF ACTION: UNC |
| |
COMMENTS: Add a proper sticker spreader. Do not make more than
2 applications/season. Do not feed treated vines, forage, or crop residues to meat or dairy animals. |
| |
| D. |
SULFUR# |
15–20 lb |
24 |
0 |
| |
MODE OF ACTION: Unknown. An inorganic insecticide. |
| |
COMMENTS: Do not apply when temperature exceeds 95°F or use on sulfur-sensitive varieties. Not effective on Pacific mites. |
| |
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
L. D. Godfrey, Entomology, UC Davis
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
C. B. Fouche, UC Cooperative Extension, San Joaquin County
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties
Top of page
|
