Moss and Algae = Slippery Sidewalks

Living in the tropics, people are often plagued with unsightly and dangerous moss and algae growing on driveways and pathways around their homes.  When the rain stops, the green growth will dry but will regenerate again with the next rain. 

There are many different products on the market to help clean up the driveway.  Look at the active ingredients on the label; most products will contain bleach,  soap, or a form of copper. Be sure to follow the directions on the label.  Most products are applied and remain for a while and then washed off with a hose or scrapped with the help of a shovel.  At times the buildup is so great that a power washer is needed. Bleach is often recommended at one cup per gallon of water. 

When using copper and bleach, there is always the potential for these products damaging desired plants either from the direct spray or from the solution saturating the soil. Take caution when spraying near desirable plants. The damage is lessened in high rainfall areas through the leeching action of the rain.

Another option is to use one cup of vinegar per gallon of water; bleach is sometimes added to fortify the solution. An application of Roundup herbicide will kill the algae and moss, but the plant residue needs to be scrapped away. 

Lichens and Moss on Trees

Should I remove the moss and lichens growth that are growing on the trunk of my tree?

The light to dark greenish growth growing on the limbs and trunks of trees can either be moss or lichens. Lichens is a bit odd in that it is actually two different organisms, a fungus and an alga living together. It is the fungus that provides the shape with the algal cells growing in a layer near the top of the fungal structure. The algae manufacture food, a process called photosynthesis, for both the fungus and the algae: a symbiotic relationship.The lichen structure is usually grayish-green in color, paper-like, and forms small circular to irregular-shapes.

Lichen and moss are frequently seen growing on twigs and branches, especially under moist conditions. When wet from rain or dew, they are active growers but when dry, they stop growing. They do not die but lie dormant until the next rain starts.

 They are both considered harmless.  Although these organisms attach themselves to the tree, they are not pulling vital nutrients from that tree. It is often thought that lichens and moss are injuring a tree because they are growing so well and the tree is declining. There is a relationship between the vigorous growing moss/lichens and the decline of the tree, but not the way most people think. The trees are growing poorly not because of the moss or lichens, rather just the opposite. Trees decline first, shedding leaves and thus allowing more light to penetrate to the bark of the trunk and limbs. This, in turn, will cause a new growth spurt in the moss or lichens. This growth spurt is an indication that some other requirements of the plant are not being met. Check and make sure there is no insect infestations (scale, aphids), no old weed- whacker damage and make sure the tree is adequately fertilized. 

If you are troubled with this type of growth on your trees, take heart in the fact that most lichens will not grow in a smoky or polluted atmosphere.

Moss/Algae on sidewalks

After abundant rainfall, what to do about all the slippery growth on driveways and paths around the home. (often referred to as slimy blobs of olive green matter similar to what one would expect floating on a pond).

Living in the tropics, we are often plagued with unsightly and dangerous moss and algae growing on driveways and pathways around our homes.  When the rain stops, the green growth will dry up but will regenerate again with the next rain. 

There are many different products on the market to help you clean up the driveway.  Look at the active ingredients on the label; most products will contain bleach, copper, or soap. Be sure to follow the directions on the label.  Most are sprayed on, left for a while and then washed off with a hose – sometimes with the help of a shovel/scrapper.  Often times the buildup is so great that a power washer is needed. Bleach is often recommended at one cup per gallon of water. 

When using copper and bleach, there is always the potential for these products damaging desired plants either from the direct spray or from the solution entering the soil. Take caution when spraying near desirable plants. The damage is lessened in high rainfall areas through the leeching action of the rain.

Another option is to use one cup of vinegar per gallon of water; bleach is sometimes added to fortify the solution as vinegar alone may not always work.   An application of Roundup herbicide will kill the algae and moss, but the plant residue still needs to be scrapped off.