Question
QUESTION: I have a tree that has been leaking sap for 4 years now. I noticed that my roof, car , driveway and front house is stained with this sap. Also when the tree blossoms my grass dies. Is this sap dangerous? the city sprays it once a year but it is a reoccurring problem. I asked the city to cut it down and maybe replace it but they don't want. what argument can i use to convince them?

ANSWER: Sounds like either an insect called an aphid or a scale insect. Both insects will suck the plant juices fro the tree and secrete a substance called honeydew which is high in sugar content and sticky. This will rain down like a light mist. The sap is not dangerous but will make a mess. These insects can be controlled with the use if a systemic insecticide. One of the newer ones is Bayer Advanced Tree & Shrub Insect Control Concentrate. It is applied to the soil under the tree and the roots take the insecticide to the limbs and foliage and when the insects suck the juices they are killed. Spraying can be effective but has to be done at the right time of the year and complete coverage of the folaige is needed. I would get the City to use the Bayer Advanced Tree & Shrub Insect Control Concentrate on the tree.

---------- FOLLOW-UP ----------

QUESTION: Apparently it is the aphids causing the problems. And it is extremely difficult or impossible to get rid of them. The city has told me that I have a severe case. The city has been spraying for 4 years now, and unsuccessfully at that. Also what time(s) of the year should the spraying be done?
Thanks again for your kind advice.

Answer
Aphids can be treated any time of the year that the tree has foliage. The spring would be the best as soon as the leaves are full. The key to control is using a systemic insecticide as a spray or a soil applied. These get into the trees system giving longer control. The other important item is complete coverage if using a spray. The aphids will build up fast if not completely controlled. Sounds like this is what is happening-- the city is spraying but not completely covering the foliage and more than likely not using a systemic insecticide.

Contact Insecticides Numerous contact insecticides are registered for aphid control. Since aphids are often placed under considerable pesticide pressure in field crops and greenhouses, they may be resistant to certain categories of insecticides. Therefore, if you do not obtain reasonable control, consider rotation to another insecticide. Contact insecticides currently registered for aphid control include: acephate (Orthene), bifenthrin (Talstar), chlorpyrifos (Dursban), diazinon,  malathion, nicotine sulfate, pyrethrum, rotenone, resmethrin, and tetramethrin + sumithrin.

Chemical Control - Systemic Insecticides Several systemic insecticides are useful in aphid control. Aphids have sucking mouthparts and are thus very susceptible to pesticides located in the plant vascular system. Some of the systemic insecticides also have contact activity. Systemics injected or applied to the ground are less harmful to beneficial insects. Systemic insecticides include: acephate (Orthene).