Common Rose and Garden Pests

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Austin Morris
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1 Image: Common Rose and Garden Pests E. Guiberson Road, Fillmore, California (805)

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3 Table of Contents Arthropod Pests Aphid 2 Mites 4 Thrips 6 Rose Slug 8 Leaf Cutter Bees 9 Whitefly 10 Mealybug 11 Diseases Rust 12 Powdery Mildew 13 Black Spot 14 Virus 15 Root Gall 16 Abiotic Damage General Toxicity 17 Round-Up Damage 18 Safety 19 Quick Reference Product Tables 20

Page 2 Aphid Aphids are a common pest on roses throughout spring and into summer. They reproduce asexually and at an incredible rate. Some aphids give birth to young that are already pregnant.

4 Page 2 Aphid Aphids are a common pest on roses throughout spring and into summer. They reproduce asexually and at an incredible rate. Some aphids give birth to young that are already pregnant. This ability to grow in number so quickly can produce massive infestations. They feed on the plant by inserting their straw-like mouthparts into part of the plants circulation system called the phloem. This is the part of the plant that moves sap filled with sugars down from the leaves. The aphids excrete most of this fluid out as honeydew. This can accumulate on the plant and grow black sooty mold. This is unsightly as well as bad for the plant.

Aphid Page 3 Control Aphids are very fragile but prolific, using a high pressure water nozzle attached to a hose and blasting them off may be sufficient for control.

5 Aphid Page 3 Control Aphids are very fragile but prolific, using a high pressure water nozzle attached to a hose and blasting them off may be sufficient for control. You will need to do this up to several times a week. Light Horticultural Oils, Insecticidal Soaps, or Neem Oil are all good options for control of aphids. They have very little residue which is great from a safety standpoint but may require reapplication. Systemic insecticides such as imidacloprid, have a long residual but will also kill more then just the aphids including beneficial insects like ladybugs and other predators There are many predators and parasitoids of aphids. Lady Beetles are very popular and fun but only marginally effective. Lace wings are a better choice in natural control of aphids.

Page 4 Mites Mites are arachnids, the same class a spiders. These guys however are extremely tiny (less then 1mm) and feed by sucking the juices out of individual cells on the leaf.

6 Page 4 Mites Mites are arachnids, the same class a spiders. These guys however are extremely tiny (less then 1mm) and feed by sucking the juices out of individual cells on the leaf. This produces a stippling on the leaves that can be yellowish gray. Some species of mites produce webbing which can be seen on the undersides of leaves. Mites reproduce very quickly and a single female can lay hundreds of eggs. The most common mite found on roses are Twospotted Spider Mites (Tetranychus urticae) named for the two black splotches found on the adults back (see picture bellow). Adult Egg

7 Mites Page 5 Mite Damage Control Mites like dusty leaves so over-head watering can reduce your susceptibility to mites. This can also increase your susceptibility to fungal diseases, so keep this in mind. Light Horticultural Oils, Insecticidal Soaps, or Neem Oil are all good options for control of mites. They have very little residue which is great from a safety standpoint but may require reapplication. Be sure to target the underside of the leaves when spraying. There are very few specific miticides available on the market for homeowners. Many products that have mites on the label kill more then just the mites including beneficial insects like ladybugs and other predators.

Page 6 Thrips Thrips are everywhere and feed on many weeds, crops and ornamental plants. They are extremely tiny, rarely getting larger then 1mm as adults.

8 Page 6 Thrips Thrips are everywhere and feed on many weeds, crops and ornamental plants. They are extremely tiny, rarely getting larger then 1mm as adults. You can tap almost any flower on a piece of paper and you will see little yellow thrips running around on the paper. Thrips feeding will cause scaring on fruit, flowers and leaves (see picture on opposite page). Thrips do have wings and can fly. However due to their small size they are generally blown around and are part of what is called the arial plankton. Other tiny arthropods such as aphids and mites can also be found being blown about in the wind. The most common thrips found in flowers is the Western Flower Thrips.

Thrips Page 7 Thrips Damage http://www.colostate.edu/depts/coopext/4dmg/pests/thrips.

htm Control Good garden maintenance should keep thrips population at a low level.

9 Thrips Page 7 Thrips Damage Adult thrips next to a Dime Control Good garden maintenance should keep thrips population at a low level. This includes deadheading and removing weeds. Thrips are very hard to control as the damage they do to the flower is caused during floral development inside the bud. Some systemic pesticides may be effective at controlling thrips.

Page 8 Rose Slug Rose Slug is not actually a slug, it is in the same insect

They feed on the leaf by chewing holes in the middle of the leaf (see

Control Products containing active ingredients such as imidacloprid or

10 Page 8 Rose Slug Rose Slug is not actually a slug, it is in the same insect order as bees. The adult is called a saw fly and the larvae are the slug. They feed on the leaf by chewing holes in the middle of the leaf (see picture below). Control Products containing active ingredients such as imidacloprid or spinosad are a good choice for this pest. See the Quick Reference Table on page 21 for specific products. Rose Slug Damage Rose Slug Rose Slug Adult

These bees much like honey bees pollinate many crops in your garden.

11 Leaf Cutter Bees Page 9 Leaf cutter bees can be mistaken as a pest but should be thought of more as a compliment. The bees use the pieces of leaves to build nests for their young. They are usually only present in healthy ecosystems. These bees much like honey bees pollinate many crops in your garden. We recommend bragging to your friends about them and letting them have a few leaves from your garden. Leaf Cutter Bee Damage

Page 10 Whiteflies Whiteflies look like tiny moths but are actually in a completely different order of insects called Hemiptera along with things like aphids.

12 Page 10 Whiteflies Whiteflies look like tiny moths but are actually in a completely different order of insects called Hemiptera along with things like aphids. They, like aphids, feed on the phloem of the plant and can make massive amounts of honeydew. They have also developed resistance to many pesticides used in agriculture and are a huge pest in crops such as tomatoes and squash. They can also transmit many plant viruses. They are rarely a problem on roses but may crop up in your veggie garden. Control Control for whitefly is very similar to aphid. See Quick Reference Table on page 21 under aphid control. Larvae Adult

Mealybug Page 11 Mealybug are in the same order as whiteflies and aphids (Hemiptera) and also feed on the phloem of the plant. They too can make massive amounts of honeydew.

13 Mealybug Page 11 Mealybug are in the same order as whiteflies and aphids (Hemiptera) and also feed on the phloem of the plant. They too can make massive amounts of honeydew. Mealybug like to live in the cracks and crevices of the plant as well as the underside of the leaves. They are easily identified by the cottony texture of their egg cases that they deposit on the leaves. They are very hard to eradicate from your garden by use of chemicals but usually will die back as the weather changes. Control Good spray coverage is very important as mealybug like to hide in hard to spray places Heavy Horticultural Oil dormant sprays are a good tactic to try during winter. Products such as Imidacloprid or other systemic insect killers work well during the spring and summer. Adult

14 Page 12 Rust Rust is a fungal disease that literally looks like there are little bubbles of rust on the leaf. This orangey dust will rub off easily with your finger but this will not stop it from coming back. Rust is sensitive to temperature and humidity so it is generally only a problem in spring and in moist environments. Control Water plants in the morning instead of the evening to avoid high humidity over night. General fungicides will control black spot. See quick reference guide (page 20) for specific products. Rust Spores on the leaf

15 Powdery Mildew Page 13 Powdery mildew is a fungal disease that is easily identified by the white/gray powder that forms on the stems and leaves. This disease can cause flowers to abort and leaves to die. Powdery Mildew loves moist nights and dry afternoons and is a huge problem along the coast and in early spring. Some varieties of roses are very susceptible to powdery mildew and should be avoided on the coast. In general glossy foliage is a good indication that the rose will be resistant to disease. Control See control for Black Spot (page 14) Powdery Mildew

16 Page 14 Black Spot Black spot is also a fungal disease like powdery mildew and rust. It causes large black blotched on the leaves. Many sprays are available for this but the damage you see is permanent. After treatment however the new leaves should not develop black spot. Control Water plants in the morning instead of the evening to avoid high humidity over night. General fungicides will control black spot. See quick reference guide (page 20) for specific products. Black Spot symptoms

Virus Page 15 Virus is a fairly uncommon sighting in roses. Virus in roses is generally transferred by infected parent material for grafting and/or rootstocks.

17 Virus Page 15 Virus is a fairly uncommon sighting in roses. Virus in roses is generally transferred by infected parent material for grafting and/or rootstocks. Roses are usually screened for virus before they enter the market. Generally they will cause yellow patterns on the leaves and are harmless to the plant. If they bother you the only solution is to remove that plant and get a new one. Virus can also lay dormant in the plant for a long time and may crop up in older plants occasionally. Viral Chlorosis

18 Page 16 Root Gall Root gall is a bacterial disease that causes uncontrolled growth of the root tissue similar to cancer. This is highly contagious between plants through mechanical transfer on implements such as shovels and clippers. Control Remove the plant immediately and dispose of the plant in the trash. Do not compost it! If you do have a plant with root gall be sure to sterilize your clippers and any other tools that come in contact with the plant with a bleach solution. Root Gall

General Toxicity Page 17 Plants can experience toxicities from may sources including too much salt, fertilizer, or pesticides. These will generally present as dead leaf edges as pictured below.

19 General Toxicity Page 17 Plants can experience toxicities from may sources including too much salt, fertilizer, or pesticides. These will generally present as dead leaf edges as pictured below. If it is a salt/fertilizer issue in the soil then the best way to remediate the issue is to leach the root zone of the plant with a heavy watering. If it is a pesticide issue then the plant should grow out of the damage. This type of damage can also be caused by over-watering and saturating the roots causing them to begin to rot. In this case back off your watering schedule and allow the soil around the plant to dry out before watering. This happens very commonly when the rose is on the same sprinkler timer as the lawn. Necrotic leaf margins

Page 18 Round-Up Toxicity Round-Up (chemical name: glyphosate) is very toxic to roses. So much so that even a fine mist drifting over from the side walk can cause amazing problems.

20 Page 18 Round-Up Toxicity Round-Up (chemical name: glyphosate) is very toxic to roses. So much so that even a fine mist drifting over from the side walk can cause amazing problems. Round-Up causes the plant to produce alien-like little narrow misshapen leaves. The plant will survive this but can take up to 2 years to grow out of it. Another common cause of this is using the same sprayer for herbicides that you use for insecticides and fungicides. Even a well washed sprayer can have enough residue to cause this to happen. It is always best to have two sprayers: one dedicated to herbicides and the other things you put on your plants. Round-Up Damage

21 Safety Page 19 Some Quick Safety Tips: All pesticides have labels on the bottle. ALWAYS READ AND FOLLOW THE LABEL! Only spray when you need to and know what you are spraying for. Some pesticides are very specific and may not work on what you think you have, so get it identified. Wear proper Personal Protective Equipment (PPE) If you don t know or don t understand something when it comes to spraying consult a professional at a nursery or garden center. We are happy to help you get it right and do it safely. Keep records of what you spray, when you spray, and for what you are spraying. This will help you keep track of pest problems and if an issue comes up you can easily check your notes.

22 Page 20 Quick Reference Product Tables Ro un

23 Quick Reference Product Tables Page 21

24 Records Issue Material Date

Pest Management in Vegetable Gardens. Pam Brown Extension Agent Emeritus, Gardening Coach Pampered Gardeners, LLC

Pest Management in Vegetable Gardens Pam Brown Extension Agent Emeritus, Gardening Coach Pampered Gardeners, LLC pamperedgardeners@gmail.com Pest Management Involves: Providing proper cultural practices