Guava Grower’s Tips

  1. How to extend the shelf life of harvested guava?

    • During storage, biochemical changes affect the texture and quality of guava fruits. Calcium, as a constituent of the cell wall, plays an important role, which influence cell wall strength and the last barrier before fruit damage.
    • Pre-harvest calcium spray is one of the most practices improving fruit characteristics towards the end of the harvest period. Calcium spray during fruit development and maturing provides a safe mode of supplementing sufficient calcium to fresh fruits.
    • Calcium is highly immobile in plants and therefore its deficiency first affects young growing shoots and the end part of fruits. Calcium is taken-up by the transpiration stream through the xylem. Hence, conditions such as high temperature or uneven watering will slow down the calcium uptake.


    • Foliar applied calcium is phloem immobile, and will not traveling into the fruit. Foliar calcium mainly to reduce the sink pressure at the tree canopy, allowing more calcium from soil to travel up through the xylem to be allocated to the fruits.
    • A practical approach is combination of calcium fertilizers through soil application and foliar application. Different calcium fertilizer will react and uptake by plant by different mode and speed. Recommendation of combination usage as following:
      1. CALBOR: Foliar application + fast soluble & available = supply calcium to whole tree canopy, reduce calcium sink pressure on canopy, then allow more calcium inside soil to move to fruits.
      2. NICALBOR: Soil application + fast soluble & available = supply quick calcium to whole plant and fruits during peak fruiting stage.
    • SULKA: Soil application + slow soluble & available = supply calcium to whole plant and fruits for a longer period.

    2. Can I foliar spray Humic acid or/and fulvic acid to my guava trees?

      • Humic and fulvic acids are both humic substances (along with humin). However, there are a few key differences that impact their benefits and how each are best applied.
      • Humic acids are large molecules that function best in soil. Fulvic acids are much smaller molecules that work well in both soil and foliar application.
      • Humic acids unlock nutrients and bind to them, making them available for uptake into plants. They stimulate microbial activity in soil, increase water retention, and stimulate root and shoot growth.
      • Fulvic acids bind to nutrients and transfer those nutrients into plants.
      • Humic acids can be thought of as the roads that allow for essential exchanges between the plant and soil. Fulvic acids can be thought of as the cars that carry nutrients from the soil into the plant.


      • FULVITA Soluble; apply either as foliar or drenching.
      • Hulmino granule; apply as soil application. Granular humic acid (10%) plus amino acid (10%).

      3. How to induce flowering on mature guava trees?

        • Potassium Nitrate is commonly used to break dormancy of buds, particularly flower buds. Tree needs to have adequate nitrogen reserves for flowering and subsequent fruit formation.
        • Potassium Nitrate increase internal ethylene concentrations of shoots and ethylene forming enzyme (EFE) activity in leaves that’s initiation of flowering. Once gibberellins levels fall below a threshold level, starch can start to accumulate, allowing the tree to flower.
        • After sufficient starch has accumulated, floral initiation will ensue. Potassium Nitrate may active those quiescent buds for floral initiation.
        • Solution:
        • Foliar spray of 1.5% to 2.0% of Potassium Nitrate KM SANGRALINE PN 13-0-46+IODINE is able to provide more number of flowers, speed up flower blooming, better fruit set, better fruit retention, better fruit weight and yield.
        • Other than use for flower induction, Potassium nitrate KM SANGRALINE PN 13-0-46+IODINE also become efficient source for Potassium and Nitrogen source. Nitrate is the preferred nitrogen source. A few of the benefits of using potassium nitrate KM SANGRALINE PN 13-0-46+IODINE is that nitrate can be readily absorbed by the plant, limits the uptake of chloride, avoids acidification of the soil. Meanwhile, potassium promotes photosynthesis and the production of proteins, intensifies the transport and storage of carbohydrates, improves water use efficiency.

        4. What are the tips to get good effect from foliar application to guava trees?

        • Few tips for foliar application to guava trees as following:
          • Spray only during early morning or later afternoon, when the temperature is lower.
          • Spray when less windy.
          • If the mixture phytotoxicity is unknown, do test spray for small area.
          • Consider spray concentration according to label and avoid concentrated sprays, as they might scorch leaves.
          • When preparing spray mix, it is advisable to keep the pH of the spray solution at level of 5.5 -6.5, to improve the spray efficiency.
        • Foliar application is an efficient method to get complement of the plant nutrient requirements, among the benefits as following:
          • Complement fertilizer: especially for poor root, poor soil, low nutrients in soil, and when nutrient fixation happened (high pH).
          • Correct nutrition: when certain deficiencies noticed.
          • Growth boosting: quick response during certain growth stages.
          • Special effects: flower induction, sun protection, reduce stress.
        • Selection of nutrient ratio as foliar application is essential to make sure the foliar application provide the targeted nutrients based on certain growth stage. NISOL series provides complete range of water soluble fertilizers suitable for foliar application.