In the absence of chemical analysis of soils or foliage, the interpretation of visual symptoms requires expertise and local knowledge. Look for other symptoms that may identify insect, disease or animal damage. Also consider soil conditions, ground vegetation, and rainfall patterns to infer drought. If foliar appearance in a stand can be reliably interpreted to indicate nutrient deficiency and sufficient response is anticipated to make the treatment economical, the site can be assigned a high priority for fertilizing. However, an absence of visual symptoms does not preclude the possibility of growth limiting nutrient deficiencies.
Foliar analysis is a useful method of indicating possible nutrient deficiencies.
Foliar analysis should only be undertaken after a candidate stand meets all other biological, operational, and wood supply criteria. Because of the cost of sampling, foliar analysis should only be done on sites which have the potential for a return on investment. It is also important to assess soil and site conditions in conjunction with foliar analysis in order to facilitate the interpretation of analytical results. Tables 1 and 2 in Appendix 2, show interpretations of macro and micronutrient foliar concentrations. Consult a tree nutrition specialist when interpreting results of foliar analysis.