The roots of plants need a constant supply of oxygen at all times. Overmulching kills the roots of shallow-rooted plants by suffocation. Symptoms of too much mulch include chlorotic foliage (symptoms often resemble iron deficiency), abnormally small leaves, poor growth and dieback of older branches. Disease organisms that are active under conditions of low oxygen and excessive moisture can become active and attack the roots. Sometimes the old root system will be rotted as the plant tries to send out new roots into the mulch layer. Excessive amounts of mulch applied around tree trunks can lead to cankers on susceptible species
To keep tools rust-free, keep them clean and dry by wiping them off with a dry clean cloth before you put them away. To combat rust and corrosion that is caused by humidity, occasionally coat all metal surfaces with light oil. If you live in a humid climate or keep your tools in the basement, a dehumidifier will help.