What Causes Tea Rose Leaves to Drop?

• Roses need to be monitored for pests, fungus or disease to prevent leaf drop. Ryan McVay/Photodisc/Getty Images

  A variety of conditions including cold temperatures, fungus or disease, pests and poor soil conditions can cause tea roses to lose their leaves prematurely. Rose gardeners should be familiar with the various threats that can affect the health of tea roses to extend the blooming cycle and ensure that the roots remain healthy.

Temperature

• A sudden cold snap or a frost may trigger a rose to lose leaves. Frost burns the leaves, and cold temperatures signal the tea rose that it is time to divert all energy back to the roots for a dormant period. Do not plant new roses before all danger of frost has passed, and protect established roses with straw, mulch or an inverted paper bag if you think a frost may occur.

Black Spot

• Black spot is a common fungus usually brought on by sustained periods of wet, humid and warm conditions in the spring and summer. Black spot, like its name, appears on leaves as round black spots with a yellow circle around the spot. New rose canes can also be affected. The fungus can move from plant to plant easily and should be controlled with a fungicide, proper watering techniques, and good air circulation between plants.

Rust

• Rust, stem canker, botrytis blight and powdery mildew are fungi that will damage or hinder the rose's ability to provide energy to the roots and can severely stunt or kill a tea rose. Treatment of all fungi types should be applied to the leaves and affected canes only, with great care taken to avoid contact with blooms. Fungicide and pesticide chemicals can harm beneficial pollinators.

Pests

• Spider mites, thrips, rose leafhopper, rose scale and other rose pests that have sucking mouth parts will feed on tea rose leaves until premature leaf drop occurs. Mites can be controlled by a hard spray from a garden hose or the application of insecticidal soap or horticultural oil. Be sure to treat or spray the underneath of leaves to remove or kill hidden mites, eggs or larvae.

Soil Conditions

• Roses do not like standing water and should be planted in an area that has good drainage. They also will not thrive in drought conditions or compacted soil. Tea roses need fertile soil for best results. An organic mixture or inorganic mixture such as a high phosphorus fertilizer can be worked into the soil during planting, or carefully worked in a few times during the summer with a hand spade.