Annual and Perennial Links

Growing herbs in the home garden

Rare, threatened & endangered plants

Herbaceous Garden Plants - A Distance Learning Class

Cornell's
Flower Growing Guide

Herbaceous Perennial Trials

Pests of Annuals and Perennials

Daylily Rust

Biological Control in the Greenhouse

Integrated Pest Management for Bedding Plants

Cornell's Invasive Plant Program
Have you seen these plant pests?

North Carolina Insect Notes

Frequently Asked Questions

Look in the links above for a specific topic or scan the questions below. Questions are arranged by date so you may want to jump down to the month when you are experiencing trouble. Follow the links within the answers for a complete description of the insect/disease cycle and discussion on causes and control.

A. Go to the Cornell Explore web site , click on "flowers", then "guided search", and scroll down to "site characteristics". This will give you a list of flowers suited to your site.

A. Hollyhock rust causes orange spots on leaves which turn brown and die. Pick off infected leaves as noticed or if severe use fungicides, like sulfur. Destroy all plant parts at end of season.

A. First, I would caution against using a pesticide before identifying the cause of the trouble. Go to Using Pesticides Safely for more information. From your description, it sounds like the culprit could be flea beetles. They are very small, iridescent black colored beetles that cause tiny shot holes in foliage of a number of plants. They can be difficult to control, as you've discovered. You didn't mention what insecticide you applied to the plant. To choose the appropriate insecticide, look for the name of the pest and the host plant on the label. Follow the label directions for application methods.

Slugs
Q. 7/13, Something is eating holes in my hostas. Every morning I find new holes but never seen anything eating them. What is it?

A. Slugs and snails are mainly active at night and eat the leaves of tender vegetables, annuals and perennials. Here are a few control options:

• Hand picking slugs can provide limited control, which can be tedious, but avoids the use of chemicals.
• Traps are a good option: shallow pans of stale beer, or yeast dissolved in water, placed in 1 inch deep pie pans or similar containers are very attractive to slugs- they crawl in and drown a "happy death". Pans should be placed about 10 feet apart throughout the garden and emptied and refilled as slugs accumulate, or as rain dilutes or the beer evaporates. Overturned grapefruit skins and old boards are sometimes used as traps. Slugs tend to accumulate under such places during the hottest, driest part of the day. Handpick and destroy slugs as found.
• Commercial slug poisons containing iron phosphate sold under the trade names Slug-go or Escar-go can be purchased. Baits are applied to the soil surface, not directly to plants. It is recommended to set out baits before plants are up or transplants are set out, as slugs are more likely to find and feed on baits when other food is not readily available. When using pesticides, always read the label. More on Slugs and Snails.

Some hostas with heavy-textured leaves have a possible slug resistance. According the American Hosta Society these varieties are

8/4 Q. After digging up an ailing iris rhizome, I discovered it was inhabited by big white "larva" type pests and nothing was left but a hollow shell of the plant. What do you recommend to rid the soil area and rhizomes of these?

A. The iris borer can be controlled by removing plant residue (old leaves especially near plant base) each fall or early spring before new growth begins. By removing old foliage you can destroy eggs. Remove damaged leaves as soon as you see feeding and discard damaged rhizomes.

For control, beneficial nematodes can be used for control of larvae feeding in the rhizomes when soil temperatures are above 50*. Look in specialty catalogues for sources.

Or, Chemical control can be obtained by applying a pesticide when growth is 5-6" high. Follow all label directions.

A. I assume the container is in shade and is receiving ample irrigation- these are a must for impatiens. I suspect a balanced fertilizer would help green the plant up. As with all container plantings, fertilization is very important in order to keep plants healthy.

9/10 Q. We have found an area on our property that has these flowers (Closed Gentian) -is it okay to dig them up and transplant them to our flower gardens.

A. New York State's Botany Program lists Closed Gentian as an "exploitably vulnerable native plant likely to become threatened in the near future". This means that due the tendency of people to over pick this plant, it may disappear from the wild. However, It is legal to dig up this plant (almost any plant actually) as long as you have permission of the property owner. I would suggest that you only dig up one of the plants, to move to your garden. Closed gentian likes a moist but well drained soil and if your garden does not offer similar characteristics, it will die. It would be a shame to loose it from the garden AND from the site where you originally found it.

A. Squirrels may dig up flower bulbs. Newly planted bulbs can be protected with 1-inch-mesh poultry wire. Dig a trench slightly deeper than
the desired depth of planting and fit the poultry wire in the bottom. Add dirt and plant the bulbs. Place another strip of poultry wire over the plantings so that the bulbs are completely encased, and finish covering with dirt.

Indiscriminate use of pesticides introduces unneeded chemicals into the environment, puts yourself at risk of contamination, possibly kills beneficial insects and could lead to pesticide resistance in pest insects. Before choosing an insecticide, ask yourself how much damage you can withstand. If the damage to the plant is only aesthetic, your first option is always to do nothing. To choose the appropriate insecticide, look for the name of the pest and the host plant on the label. Always read the label and follow the directions for application methods.

This publication may contain pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registrations, some of the suggestions given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author and Cornell Cooperative Extension assume no liability resulting form the use of these guidelines.