NC Pest News – May 31 2013

— Written By Nikki Davis

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE
North Carolina State University * College of Agriculture & Life Sciences
Dept. of Entomology * Box 7613 * Raleigh, NC 27695 * Ph: (919) 513-8189

NORTH CAROLINA PEST NEWS
Stephen J. Toth, Jr., editor
Volume 28, Number 8, May 31, 2013

CAUTION: The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.

FRUIT AND VEGETABLES

From: Emma Lookabaugh, Plant Disease and Insect Clinic, Chris Gunter, Extension Vegetable Produc-tion Specialist, and Barbara Shew, Extension Plant Pathologist

No Joke: Tomatoes are Cracking Up

Tomatoes are cracking up after the recent rains, but growers are not amused. Recently, we’ve seen in an increase in the amount of tomato surface cracking. Tomato cracking is an abiotic disorder of tomato fruits that is associated with growing conditions. When tomatoes are left on the vine too long or during periods of rapid fruit growth, the tomato epidermis (or skin) does not have enough elasticity to compensate for the sudden growth. Eventually the skin splits and bursts.

There are two main types of growth cracks: 1) radial cracking, which is splitting of the skin from the stem scar towards the blossom end, and 2) concentric cracking, which is splitting of the skin in a circular pattern around the stem. Radial cracks occur during humid, hot weather. Concentric cracks occur during rapid fruit growth associated with rainy weather following a period of dry weather. The earlier growth cracks occur during fruit development, the more damaging they are. Growth cracks can provide the perfect entry point for secondary fruit rotting organisms.

The most important means of controlling growth cracking is maintaining a steady, adequate supply of water or irrigation flow, especially during hot, dry conditions. Avoid over and under irrigating. Mulching also will help prevent dramatic fluctuations in soil moisture. Be especially wary if weather was cool and overcast followed by sunny, hot, and dry periods, and then high humidity and rainfall. Keeping foliage healthy and disease free is also critical. If the fruit lacks leaf cover, cracking can be more of a problem. Remove mature fruit right after heavy rains to prevent cracking. Follow recommendations from Cooperative Extension about plant nutrition, because high nitrogen and low levels of potassium can contribute to fruit cracking. Some varieties are more prone to cracking and can show cracking when the fruit are still green. Even varieties that show some resistance to cracking in the green stage may crack once the fruit starts turning red. Plum varieties like ‘Heinz’ and ‘Marglobe’ crack less than cherries and the larger fruited varieties like “Better Boy.” If you have a history of tomato cracking in your tomatoes, you may try switching to one of these varieties, ‘Daybreak’, ‘Jet Star’, ‘Pink Girl’, ‘Monte Carlo’, ‘Mountain Fresh’, ‘Mountain Spring’, and ‘Spitfire.’ New varieties are released regularly, so check with your local Cooperative Extension agent for latest variety recommendations for tomatoes.

ORNAMENTALS AND TURF
From: Steve Frank, Extension Entomologist

Hawthorn and Azalea Lacebugs

Azalea and hawthorn lacebugs started hatching last week. Now we see a mix of adults and nymphs. Hawthorn lacebugs feed on pyracantha, serviceberry, and cotoneaster. Azalea lacebugs feed primarily on azaleas. Both cause stippling damage visible on the top of leaves and leave fecal spots on the bottom of leaves. For more information on lacebug management, see Ornamental and Turf Insect Information ENT/ort-39 at https://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/ort039e/ort039e.htm. Imidacloprid will kill both pests, but should be used on plants that are flowering or that will flower soon due to negative effects on pollinators (http://www.xerces.org/wp-content/uploads/2012/03/Are-Neonicotinoids-Killing-Bees_Xerces-Society1.pdf).

Woolly Apple Aphids

This week we noticed woolly apple aphid infestations on pyracantha bushes around campus. These aphids produce cottony fluff along the branches. When you brush away the fluff (really it is wax the aphids produce) you will see hundreds of pink or grey aphids crawling around. Woolly apple aphids have been out for a month or so, but are becoming very noticeable now. Infestations for multiple years produce large leafless patches on bushes. The aphids cause galls to form on branches and branches become black from sooty mold. Soap or oil should provide some control. Additional aphid management information: https://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note38/note38.html

Flea Beetles

Redheaded flea beetles, Systena frontalis, have become a serious pest of nursery stock over the past several years. They are an especially damaging pest because they feed on roots and leaves. They overwinter as eggs in the soil. Larvae hatch in spring and begin feeding on roots. The larvae are elongate and creamy-white. Heavy infestations may reduce root mass or girdle plants. Adult redheaded flea beetles are small, shiny black, beetles with reddish to dark colored head and long antennae. They are about 1/16 of an inch long and, as the name suggests, jump when they are approached. There are at least two generations in Delaware and may be more in North Carolina.

We found adults and adult feeding damage this week. The favored hosts are Itea, hydrangea, forsythia, and knockout roses. Adult management has been frustrating for growers who find that even frequent insecticide applications do not reduce adult abundance and damage to acceptable levels. Part of this has to do with not controlling larvae since even if you kill all the adults present in a crop (which you won’t) more adults are emerging from the soil every day. Research thus far in Delaware and grower reports indicate that Talstar, Sarfari, and Flagship provide good efficacy as foliar applications, but do not have long residual activity.

Written By

Photo of Nikki DavisNikki DavisSupport Specialist II (919) 989-5380 (Office) nikki_davis@ncsu.eduJohnston County, North Carolina
Updated on Jun 3, 2013
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