- Author: Alejandro Del Pozo-Valdivia
On Wednesday October 9th, a Brussels sprout plant sample was submitted to our Entomology laboratory for insect identification.
At the naked eye, we observed some webbing and specks on the leaf (See Fig. 1).
Fig. 1. Leaf of Brussels sprout showing some webbing and 'specks'. Affected areas are highlighted with the yellow circles.
Under magnification, we were able to see eggs, nymphs and adults of the two spotted spider mite (TSSM), Tetranychus urticae (See Fig. 2). Adults of these specimens have the two black spots on the lateral sides of the anterior end of the podosoma, the area located below their mouth parts.
Fig. 2. Eggs, nymphs and adults of two spotted spider mites on the leaf of Brussels sprout.
TSSM is one of the most polyphagous mites, having several host plants around the world. Females disperse by putting silk strands right after mating and before producing eggs. Dispersing females climb to the top of the plant and specimens are carried out by the wind. This phenomenon called ballooning, aids mites to float through the air and disperse longer distances to reach favorable host plants.
It is highly advised that Brussels sprout growers and PCAs walking this crop, pay close attention to leaves within the canopy to potentially identify the presence of TSSW in this crop.
If you believe you may have TSSM in your Brussels sprouts, please send us a plant sample at 1432 Abbott St. in Salinas for confirming identification (free service), or call us at 831-759-7359 to obtain additional information on this pest.
- Author: Shimat Villanassery Joseph
- Author: Mark Bolda
Two spotted spider mite (Fig. 1A) is a major pest of strawberry and caneberries. The spider mites lay 0.14 mm eggs (in diameter) on the undersides of strawberry leaves. Once the eggs hatch and the larvae go through three stages and molt into adult males, and reproductive females. As the name suggests, they are called two spotted spider mite because of one or more dark spots on the bottom half of each side of the body. They are typically dull or yellow colored organism but during the winter months, they undergo diapause (a resting stage) and appear as reddish or orange color (Fig. 1B) which often is confused and misidentified as carmine mite or presumably a new mite never seen before. Carmine spider mite is a bright red colored mite (Fig. 1C) but do not have spots on the either side of the body. They rarely cause economic injury to strawberry. They occurring during the winter and spring months in the Salinas/Watsonville strawberry fields. Predatory mites are also greyish, pale reddish or orange colored in general but they are shiny and moves very fast on the leaves (Video).
For further reading click the Pest Management Guidelines for mites in strawberry (http://www.ipm.ucdavis.edu/PMG/r734400111.html)
