Monday, September 25, 2017

Pest Spotlight: Cabbage Looper

Cabbage looper (Trichoplasia ni).
Caterpillars in the Greenhouse
Publication date: Jan. 1, 1994
Last updated: Sept. 25, 2017

Cabbage Looper
The adult cabbage looper is a grayish-brown moth with a wingspan up to 33 mm. The forewings have a distinct irregular, white mark.
When first deposited, the eggs are white but darken as they get older. The eggs are hemispherical with fine transverse lines and longitudinal ribs.
Newly hatched larvae are whitish with a black head and shield immediately posterior to the head. As the larvae grow, they become light green with two dorsal white stripes and two wider lateral white stripes (Figure D). The markings become less distinct in the last instar. The body tapers toward the head, and the full grown larva is 35 to 40 mm long.
Easily seen through the webby cocoon, the pupa is light green when first formed and darkens to almost black later.
The cabbage looper is found throughout the United States.
Host Plants:  
The cabbage looper larva IS a general feeder with a wide range of possible food plants. Some hosts are cabbage, carnation, snapdragon, nasturtium, mignonette, celery, tomato, beet, pea, and lettuce.
On some plants the larva has a distinctive feeding habit. The holes it makes are arc-shaped. The area of the hole is determined by the size of the larva that made it. The characteristic pattern is caused by the larva partly cutting the leaf as far as it can reach by holding fast with its hind legs.
Life History:
Because the larva of the cabbage looper lacks 2 pairs of prolegs, it is necessary for the caterpillar to arch its back in a looping fashion to move, hence the common name looper.
Eggs are deposited singly on either side of the leaf by the cabbage looper. Each female is capable of producing 200 or more eggs. Hatching occurs 3 to 10 days after the eggs are laid. There are four or five larval instars that develop in 10 to 50 days. If food is abundant and environmental conditions are favorable, only four instars develop. The larvae are strong crawlers and will travel some distance to reach a new host. If disturbed, the caterpillars characteristically curl into a ball and drop from the plant. Pupae are formed within a thin, white cocoon that may be attached to different objects or under a clod of soil. The pupal stage lasts from 6 days to as long as several months (overwintering stage). The adults are strong fliers and are active about dusk and on cloudy and cool fall days. The moths avoid strong sunlight.
  • A number of parasitic wasps and flies attack cabbage looper caterpillars, and birds and bats feed on the adult moths.
  • Bacterial insecticide Bacillus thuringiensis can be applied by home gardeners when caterpillers are small. repeat treatments at weekly intervals if plants become reinfested.
  • Use row covers to keep from laying eggs \. Clean all plant debris from garden to reduce the number of overwintering pupae. 
See more cabbage pests from NC State Extension:

Sunday, September 17, 2017

NC Cooperative Extension Master Gardener Handbook is Online!

If you would like to research all of the plant topics taught through the NC Cooperative Extension Master Gardener program, (minus the live lectures of foremost NC State horticultural professors), then visit the online EMG handbook.  
(This online handbook is an updated version of the class binders given in years past.) 

Monday, September 11, 2017

Durham's Finest Trees Deadline Oct. 1

Don't forget to nominate your favorite tree(s) in Durham with Trees Across Durham and the Durham County Master Gardeners:
Read about one of the 2017 winners, the osage orange tree at historic Stagville Plantation on the Master Gardener blog.
Photo: Yellowish-green fruit and shiny green leaves of Osage Orange tree. Photo taken by Wendy Diaz September 16, 2016.

Time for Fall Seeding of Tall Fescue & Kentucky Bluegrass

Aeration is an integral part of reseeding a healthy fescue turf in the fall.

By Grady Miller, Professor and Extension Specialist
NC State Extension, updated by Danesha Seth Carley (9/6/2017)

Fall is the best time for renovation and seeding of cool-season lawns. Temperatures are currently above normal for early September, but long range forecast predict they will begin to moderate. Hurricane season has also been active, so consider heavy rainfall in your planning as much as practical. Much of the state has been dry in July and August, so some rain would be appreciated to help make aerification a bit easier. Heavy rainfall can wash seed.

Remember that spring-established tall fescue is more susceptible to drought, heat, fungal diseases, and weed encroachment. With normal summer weather patterns, spring seeding is not likely to result in a year-long stand of healthy tall fescue. So do not delay, seed in the fall!

Young seedlings normally emerge and grow best when air temperatures are between 70 and 80 degrees. Soil temperatures need to be greater than 60 degrees for good germination. So, it is generally better to go a bit early than seeding late. If tall fescue is seeded in under less than ideal conditions (too cool or no soil moisture), you may experience a thin turf stand going into the winter. So try to get your seed out in September. If you must wait until October there is an increased likelihood of slow/low germination.

It is best to choose cultivars from the turffiles website. There is a list on TurfFiles of 2017 Top Performing tall fescue and Kentucky bluegrass cultivars. For a larger list of good performing cultivars, the 2014 lists are still a good resource: 2014 Recommended Kentucky Bluegrass Cultivars for North Carolina and 2014 Recommended Tall Fescue Cultivars for North Carolina.

If you buy a tall fescue blend, try to find one with at least one of the cultivars from the list of recommended cultivars. These grasses were chosen because they produce a high quality turf in North Carolina and have been shown to be less susceptible to brown patch. Some like to mix in a little Kentucky bluegrass (darker color and finer texture) or fine fescue (for shady areas). I do not suggest adding ryegrass to the mix as it can dominate and reduce the stand of the more heat-tolerant tall fescue. A typical tall fescue seeding rate is 5 to 6 pounds of seed per 1000 square feet. Germination will normally be in 7 to 14 days with soil moisture and suitable soil temperatures.

Before seeding core aerification is recommended to reduce compacted areas. Getting good soil to seed contact is paramount to maximize available soil moisture. The core aerification holes will capture seed and hold moisture so the tall fescue seedlings often come up as a tuft of turf from the aerification holes.

Follow normal tall fescue or Kentucky bluegrass fertilization practices as outlined in Carolina Lawns available on the website. The suggested yearly nitrogen application is about 1.0 pound of nitrogen fertilizer per 1000 square at seeding. Include phosphorus and potassium fertilizers if soil tests indicate there is a need. In the absence of a soil test, a 16-4-8 or similar N-P-K ratio fertilizer may be used this spring. Before additional fertilizer or lime is added, conduct a soil test (

To apply 1 pound of nitrogen per 1,000 square feet: Divide 100 by the first number on the fertilizer bag to determine the amount of product to be used per 1,000 square feet. Example: Using a 16-4-8 fertilizer, 100 divided by 16 equals 6.25, therefore, 6.25 pounds of fertilizer per 1,000 square feet will deliver 1 pound of nitrogen.

If irrigation is available, set your controller within current water restrictions for your area. Irrigate early in the morning to reduce water loss due to evaporation. In the fall, ¼ to ½ inch water per week of water (via rainfall or irrigation) is generally sufficient to meet the turf’s water needs. Irrigation can usually be discontinued in November without any reduction in turfgrass quality.

Since seeds and seedlings may be damaged by some herbicide applications, fall seeded cool-season grasses should not have any herbicides applied until it is extensively tillered.

It is very important that tall fescue be maintained at the proper mowing height to allow it to mature before winter and to minimize weed incidence. Studies have shown that a 3½ mowing height provides the best growth condition while minimizing disease incidence and weed encroachment. A 3 to 3.5 inch mowing height is also a good height for tall fescue + Kentucky bluegrass.

Note that warm-season grasses such as bermudagrass, zoysiagrass, centipedegrass, and St. Augustinegrass can be sodded in the fall, but it is generally not recommended due to the increased chance of winterkill. Warm-season grasses should not be seeded in the fall as there is inadequate time for maturity before the first expected frost.