For control of needlecasts, fungicides are considered economical for:

Fungicides are considered economical for only young, small trees when it comes to controlling needlecasts. This is because young trees are more vulnerable to disease pressures and can suffer significant damage that affects their growth and development. The application of fungicides in these cases helps protect the trees from further damage and supports their health and establishment in the landscape.

Also, the cost-benefit analysis favors treating younger, smaller trees, as the potential losses from needlecast can be greater during this stage of development. On the other hand, mature trees can often withstand some level of stress and may not require treatment as urgently, making fungicide applications less economically justified at that stage. Similarly, while some bushes and shrubs may be susceptible to needlecasts, the treatment cost may not bring the same value for their management as with young trees.