ANSWER: An insect called a rose slug, which is actually the larva of a small sawfly scrapes the cells off the back of the leaves, only the upper epidermal layer remains. When it dries it becomes transparent. The good news is that the larva are gone. There is only one generation per year. Most have dropped to the ground under the rose and pupated until next year, when the adults emerge, mate and lay eggs to start the process all over.
CURE: Next spring spray with a systemic insecticide, so when the eggs get laid the newly hatched larva will be killed. Bayer Rose & Flower Systemic Insect Killer
2.) Overly wet soils – "My plants were looking so happy and healthy during this cool spring, then 2-3 weeks ago the leaves started turning yellow and the plant just stopped growing. What is wrong and can they be saved?"
ANSWER: This spring has been the wettest since we have been recording rainfall. Over 22 inches accumulated since March 1. When the rain saturates soil so frequently, all the air, including the Oxygen gets pushed out of the root zone, essentially drowning them. When they are damaged or dead, they can not perform their jobs – taking nutrients out of the soil solution and transporting them to the leaves. When the leaves do not get all of the "building blocks" they need, less chlorophyll gets formed. The leaves look yellow, usually in between the veins. The horticultural term is chlorosis. As the soil gradually dries out, more air and oxygen can get down into the soil. Roots can do their job and new roots can form.
CURE: Using a rooting hormone with fertilizer can help the plants recover more quickly. Root & Grow & use a garden fork to aerate the root zone, adding Espoma Soil Perfector
3.) Diseases – "My plants have a white powdery covering. What is wrong and what caused this to happen? Is there anything I can do to cure it and prevent it?"
ANSWER: Your plants have a fungal leaf disease called Powdery mildew, It is a fungus that is active during 2 different conditions – 1. When temperatures are cool or cold and there is water that stands still for 4 hours on the surface of a leaf. The spore can germinate and then inoculate the surface of the leaf. The mycelium then grows across the surface of the leaf eventually blocking the sunlight from the surface.
CURE: There are systemic fungicides that will prevent and cure the disease. Immunox will stay in a plant tissue for 14 days, preventing the disease and stopping it if inoculation has already taken place. For edibles, use one of the "Earth Friendly Naturals" as a preventative. Sulfur or Copper in sprays work very well. Re-application after rain or watering is required. Concern Copper Soap Spray or Espoma 3 in 1 Disease
4.) Wildlife damage –"Many of my plants have large notches missing, what is causing it and is there a control?" The worst pests this season are the rabbits. The fact that many people do not know is that the juvenile rabbits do not have the sense of taste or smell, so those types of repellents are not working.
CURE: The hot pepper sprays seem to be working to repel the juveniles. The secret is to keep rotating the repellents to keep the rabbits confused and not trusting of your "restaurant". Rotate with Liquid Fence, Bobbex for Rabbits and Repels-All
5.) Extra Entry – Gypsy Moth larva. This is a terrible insect that the officials have been warning us about for the last 10 years. They are here in Northern Illinois now. The larva are too large for effective control with many insecticides, so be on the watch for the adult moths, especially the females that will be laying egg masses within the next month. Contact insecticides, like Bonide Household Insect Control with 4 month residual action can kill the adults, Golden Pest Spray Oil (93% soy soil) is the only product that will saturate the egg masses and kill the eggs.