An additional tool that can be used for long-season crops such as eggplant, pepper, potato, tomato, squash, sweet corn, and pumpkin is plant tissue analysis. While leaf tissue laboratory analysis can be used to verify symptomatic deficiencies in any nutrients, it can also be used to detect sufficiency levels of critical nutrients such as N, P, K, Ca, and Mg. If performed early enough in the season, corrections can be made by topdressing, sidedressing, or fertigation. Prior to making nutrient corrections, other potential issues, such as incorrect pH, inadequate soil moisture, root disease, or insect infestation should be addressed first. Leaf tissue analysis requires collecting a representative, adequately sized sample of whole leaves from designated locations in the plant canopy. These locations vary among crop species and specific sampling and handling instructions are available from university and private laboratories. Labs will present the results from the sampled tissue alongside reference nutrient sufficiency ranges for the crop tested. Nutrient status of some crops can also be determined using laboratory testing of whole leaf petioles, and for nitrate-N and K, it is possible to test petiole sap in-field using a portable meter.