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From: Jack S. Bacheler, Extension Entomologist
Only the earliest of the limited amount of cotton planted from mid April through our recent bout of cold, rainy weather is advanced enough for economic damage from thrips. That will change quickly, however, as the three week seed treatment residual window is arriving fast for some of this early cotton. Producers should be reminded that the nematicide component (abemectin) in Avicta seed treatment does not add thrips activity beyond that provided by the Cruiser in this product. Therefore, Avicta seed should be treated with a foliar spray at the first true leaf stage, such as Cruiser and Gaucho. With the recent rainfall received by most areas of the state, activation of seed treatments and Temik should be good.
Two “sharp-eyed” consultants have found vegetable weevils in scattered early-planted, reduced till cotton fields in a four county area, which includes Halifax, Northampton, Edgecombe, and Nash counties this past week. The distribution of the small brown adult beetles is bound to be wider than this area. In the past, these insects have been reported feeding on cotton in Alabama, Tennessee, Mississippi, and in North Carolina. In the vast majority of previous cases, infestations of this pest have not caused economic damage. However, every year is different, and on a few occasions damage from this past has resulted in replanting.
Feeding is typically is on the stem of cotyledons and to some degree on the leaves themselves. The stem feeding is either partially through the stem, causing a weakening of the seedling or the stem is completely cut off. The damage is similar to that of cutworms. However, these beetles do not eat as much leaf and stem tissue as cutworms and, because most are on the soil surface, they’re far easier to find.
I hope that the cotton field in Edgecombe County had what would be considered a high population. Up to 3 to 5 of these ¼ to 3/8-inch beetles were found under or along side some individual cotton seedlings. Oddly, many of the beetles were dead or alive and on their backs, not a good sign if you’re the insect.
Both John Van Duyn of North Carolina State University and Scott Stewart of the University of Tennessee have also noted this apparent mortality and/or odd behavior. In this case, the Cruiser component of the Avicta in the field was causing some weevil mortality. Gaucho Grande, in the same chemical class as Cruiser, should cause similar mortality. One could reasonably expect that Temik would also show some activity against this pest. Under ordinary circumstances, the stand in this field would have been considered adequate to possibly good. However, because the vegetable weevils had thinned the stand considerably, because we could easily find what appeared to be additional healthy weevils, and because further stand thinning could be expected, we felt that treatment was warranted. In an adjacent convention till cotton field, it took a while to find our first weevil. I hope that holds up.
Stand checks for this pest in reduced tillage situations are advised, probably earlier than for thrips. This would be when cotton seedlings are emerging and the cotyledons are expanding. As with cutworms, possible treatment for vegetable weevils would a judgment call, with perhaps a 10 percent stand reduction and live weevils near the base of some seedlings being a spray trigger in the case of marginal to moderate stands.
If control is warranted, pyrethroid insecticides at low to moderate rates will probably be effective with these weevils, as they are labeled on other crops for this pest. The same would be true for Orthene. Unfortunately, in the case we observed yesterday, piggybacking spraying for this pest with a thrips or thrips plus glyphosate treatment would have been too late. On the other hand, these beetles can be around for a while -- most of the previous years’ infestations were reported during May.
With any luck vegetable weevils will again be a very minor, unnoticed seedling pest in cotton. However, this year you might want to hedge your bets and take a look -- sooner rather than later.
By next week, I will start looking how our thrips wars might be shaping up.
From: Stephen B. Bambara, Extension Entomologist
One wheat field has been seen 25 percent infested with the Hessian fly in the northeastern area of North Carolina. Symptoms of poor stand due to the Hessian fly (Hessian fly pupae in stem; photo by K. S. Pike, Washington State University) should be obvious by this time. It is probably too late for thoughts of rescue treatment. The prevailing advice is to use resistant varieties. Seed treatments are effective if you have need to grow other varieties but treatment is not free. Practice good cultural controls such as removing stubble. For more information on dealing with Hessian fly and for a list of resistant varieties, see the following sites on the World Wide Web:
http://www.ces.ncsu.edu/depts/ent/notes/Grain/Hessian/HflyAG-368.html
http://www.cropsci.ncsu.edu/smallgrains/Varieties/Varieties.html
Also visit our small grains web site at: http://www.smallgrains.ncsu.edu/.
From: Randy Weisz, Small Grain Extension Specialist
When and where: May 17, 2006 at the White Hat Seed Farm in Hertford, North Carolina
Offered: Commercial and Private Pesticide Applicator and CCA credits
Registration: opens 2:00 p.m.
Field stops: 3:00 to 6:00 p.m.
Dinner: 6:00 p.m.
For information: contact Lewis Smith at (252) 426-5428.
On the agenda: wheat response to sulfur rate and timing; early planting systems for no-till wheat; small grain varieties; small grain insect control; wheat response to split N rates; small grain disease control, fungicides and variety mixtures; and of course dinner!
From: Gerald J. Holmes, Extension Plant Pathologist
The 2006 Fungicide and Nematicide Tests and Biological and Cultural Tests were published online this week. These one-page reports on disease management trials are written by researchers from all over the U. S. as well as international authors. They are a valuable resource for anyone interested in determining the efficacy of specific products or management tactics for a specific crop and disease. All North Carolina State University employees have free access to the reports through Pest Management Network. Go to http://www.plantmanagementnetwork.org/ and click on “Resources” to access the reports. If you are asked for subscription information, go to http://www.plantmanagementnetwork.org/subscriptions/default.asp#complimentary for the complimentary registration. The reports can be searched by author, disease, product, crop, etc.
From: Stephen B. Bambara, Extension Entomologist
The wool sower gall is a distinct and unusual plant growth induced by the secretions of the grubs of a tiny gall wasp, Callirhytis seminator. If a fresh wool sower gall is held in a plastic bag out of the sun (so it will not get too hot), within one to three weeks the tiny, harmless gall wasps will emerge. The wool sower gall is specific to white oak and only occurs in the spring. Pulling the gall apart exposes small seed-like structures. The gall wasp grubs develop inside these structures. (This gall is also called the oak seed gall.) Fortunately, wool sower galls are hardly ever abundant enough to cause harm to white oaks. If the galls are actually damaging the trees, the best time to control them is mid-winter when the wasps are laying their eggs or spring just as the buds are breaking. The eggs hatch just as the new growth emerges in spring. Gall wasps invariably have alternation of generations in which one generation develops in one kind of gall (leaf gall) and their offspring develop in another kind of gall (stem gall). Wasps of each alternate generation are slightly different is size and the galls of each generation are enormously different from the parents. The wool sower gall is probably the leaf gall of this species because of its transient nature. Ornamentals and Turf Insect Information Note Number 5 (see http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note05/note05.html) provides additional information on galls. Many other galls are forming now. I'll have more information later in the season.
Scale insects in the genus Pulvinaria are reported to be currently depositing their ovisacs. The cottony maple leaf scale insect, the cottony camellia scale insect, are the two most common cottony scale insects in North Carolina. The cottony maple leaf scale (see insect note at: http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note37/note37.html) sometimes infests holly and maple, but it seems to be most common on dogwoods in North Carolina. The cottony camellia scale infests camellia and taxus. These latter two scales are in the genus Pulvinaria. Trees heavily infested with Pulvinaria scales may exhibit dieback. The month of June is a good time to spray insecticide for Pulvinaria scales as the lady beetles that specialize on feeding within the egg sacs of the scales will have then departed for their aestivating sites, and the crawlers and young scales are exposed on the leaves. Horticultural oil and Sevin are effective. The horticultural oil is a better choice since it is less likely to harm the beneficial insects. So the important thing to remember about Pulvinaria scales is that now is not a good time to treat for them because spraying kills lady beetles but not all of the eggs. Wait until late June to early July to treat.
From: Stephen B. Bambara and Christine A. Casey, Extension Entomologists
Mites that are active during cool seasons such as spruce spider mites and southern red mites should be feeding soon. Predicting insect populations is not becoming any easier these days. Watch for active colonies of cool-season mites beginning soon on coniferous and broadleaf evergreen shrubs. If you have had problems with these mites in the past, be alert because the effective time to treat will be soon. You may need a good hand lens and/or a white piece of paper on which to knock them in order to see them better. Ornamental and Turf Insect Information Note Number 77 (http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/ort077e/ort077e.htm) has more “cool” information.
From: Colleen Y. Warfield, Extension Plant Pathologist
Downy mildew of Coleus was diagnosed in four commercial greenhouse facilities in North Carolina during March and April. This disease had not been seen in the U. S. until 2005, but has since been reported in the northeast, southeast, and California. Downy mildew is active under cool, damp conditions. As a result, the past few days of cold, rainy weather could result in an outbreak of this disease in greenhouses where the pathogen is present. Click here for pictures of plant symptoms, pathogen signs, and additional information about control.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on May 1, 2006 by Stephen J. Toth, Jr.
