Black Vine Weevil Adults Are Noctural and Cause Feeding Damage at Night. Proto Credit: Steven K. Rettke of RCE

Many landscape & nursery managers consistently state that attempting to manage the black vine weevil insect (Otiorhynchus subcatus) as one of the most problematic pests they encounter. These leaf notching weevils feed on many kinds of ornamental plants including yews, rhododendrons, azaleas, laurels, leucothoe, forsythia, euonymus, hollies, viburnum, most deciduous and evergreen shrubs, ground covers and many kinds of perennials and annuals.

Controlling Black Vine Weevil adults during the month of June will prevent egg laying during the weeks of July. This beetle only has one generation a year.

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In the New Jersey region, the late weeks of September & early weeks of October are transition periods for warm season & cool season spider mite species found in landscapes & nurseries. The spruce spider mite & the southern red spider mite are the most common cool season species & they are now “waking-up” from their summer inactive period. Alternatively, the warm season two-spotted spider mite may have stopped feeding or will soon cease. They are rapidly declining & preparing to depart the leaves of their host plants if they have not already done so.

Two-spotted spider mites that produced these stippling symptoms on burning bush this summer are now entering dormancy with the arrival of autumn
(Photo: Steven K. Rettke of RCE)

Spruce spider mites that were previously in a summer dormancy are now resuming activity again on this Frasier-fir as the autumn season arrives (Salem County Nursery)    (Photo: Steven K. Rettke of RCE)

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Magnolia Scales (Neolecanium cornuparvum) & Tuliptree Scales (Toumeyella liriodendri) are both classified within the soft scale group. However, unlike essentially all the other soft scale species they have crawler emergence in August & September instead of in June & July. This fundamental difference is important to recognize in order to time sprays & achieve best controls.

Hatched 1st instar magnolia scale crawlers knocked-off branch onto white paper. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)

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During the weeks of summer, the symptoms caused by Oak Lace Bugs (Corythucha arcuata) can be a concern to some landscapers & nurserymen. Often times, the infestations are most pronounced on white oaks. From a distance, the stippling of leaves from this piecing-sucking insect can produce symptoms that are similar to those from oak spider mites or classic leaf scorch. Closer inspection determines the identity of the pest.

Oak Lace Bug Severe Symptoms in Late August.  Photo by Steven Rettke of RCE

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In most areas of NJ, the application timing of imidacloprid to nursery containers to achieve best efficacy against Oriental beetle grubs (Anomala orientalis) has now expired. The majority of eggs are laid during late June through early July and by the time August arrives, many of the grubs will have begun to molt into the 2nd instar stage. If imidacloprid is not applied until August, then some root feeding damage may have already occurred & furthermore, the larger instars will be more difficult to control. Generally, the preventative applications should be applied from early June to mid-July to achieve best results.

Next year, some nurseries may want to attempt the new Oriental beetle mating disruption pheromone that is discussed in the second half of this article.

Imidacloprid has good efficacy against Oriental beetle 1st instar grubs, but is significantly less effective against the 2nd & especially 3rd instar grubs

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During the past several weeks, significant leafhopper damage has been observed in a few nurseries within central NJ counties. Although there are many species of leafhoppers, the Potato Leafhopper (Empoasca fabae) is probably the most notorious in the northeastern U.S. states. The feeding damage can mimic herbicide injury with distortion & discoloration of foliage. Some of the common deciduous tree hosts include maple, oak, ash, & birch as well as others.  The Potato Leafhopper does not overwinter in NJ, but during the weeks of May is carried-in by upper atmospheric winds from the gulf coast states .

Potato Leafhopper & “hopperburn” symptoms on Acer rubrum  at a Burlington County Nursery   Photo Credit: Steven K. Rettke of RCE

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