Symptom - Leaves appear to have water soaked areas. Later during the day, leaves will droop. Portions or whole plant can be affected.
Causes - Caused by temperatures going below zero. Frost crystals in leaves burst cells causing water soaked areas.
Action - Cover plants with blankets or other frost protective items if only a few degrees of frost forecast. Plant sensitive plants only after danger of frost is passed. Early in the morning, hose down plants with plain water before sun shines on leaves. This will help reduce frost damage.
Symptom - Leaves may appear burnt or scorched or in some cases may be curled, twisted, distorted or stunted. Fruit can also appear deformed as well.
Causes - Common Herbicides such as 2,4-D (Killex) or Glyphosate (Roundup) etc can cause damage on desirable plants.
Action - Do not allow herbicide spray to drift onto healthy plants; spray when air is calm. Adjust nozzle to permit a coarser spray. Do not spray near desirable plants or cover the plants to prevent spray from hitting their leaves. Do not apply herbicides in granular form such as 2,4-D near desirable plants otherwise it can leach through the ground and be taken up by roots of desirable plants.
Symptom - New growth on plants becomes yellowed (chlorotic) between the veins; plants can become stunted.
Causes - Insufficent Iron in the soil or by PH levels being too high (above 7.0 or in the case of evergreens, above 6.0)
Action - Add Iron in the form of Chelated Iron according to the manufacturers directions. Get soil tested to determine PH and if PH is too high add sulfur or plenty of peat moss to lower.
Symptom - Leaves will have brown areas on the edges between the veins. Sometimes whole leaves may die and drop during late summer. Can appear in soils that are not adequately watered or too well drained.
Causes - Excessively hot and dry weather can cause Leaf Scorch. If trees/shrubs are being transported for long distances without adequate coverage or protection, the leaves may scorch from drying winds in transit. Another cause is the soil moisture levels being too low.
Action - Keep plants adequately watered especially during hot dry weather; hose down leaves to keep them cool and prevent excessive moisture loss. Keep plants sheltered or protected especially during transit.
Symptom - Older leaves appear yellow. Plant may appear stunted; green leaves are smaller than normal.
Causes - Insufficient Nitrogen in soil or low applications of fertilizer (i.e. not enough fertilizer for application or interval between applications too long).
Symptom - Small spots appear on the undersides of leaves. These spots are raised, corky, and water soaked. Spots appear more frequently on older leaves and rarely on new leaves. In old tissues, spots may become tan coloured. When the condition is severe, leaves may yellow and drop. Corky streaks may appear on the stems.
Causes - Soil that is too damp combined with cool humid air conditions. The plant is not able to move enough water out of it's leaves causing a buildup of pressure resulting in the spots.
Symptom - Extensive wilting even if soil is moist. Roots will appear brown or dark coloured and soft.
Causes - Compacted/poorly draining soil or water sitting in saucer or pot without drainage hole. another cause can be excessive watering without allowing soil to dry out.
Action - Allow soil to dry out sufficiently before watering again. Use a well drained soilless mix for potted plants and incorporate plenty of organic matter into garden every year to increase drainage.
Symptom - Older leaves have purplish cast to them. Plant appears stunted. Growth is slow. Flowers few if any. Root system is small and stunted.
Causes - Insufficient Phosphorous in soil. Ph of soil is too low (phosphorus becomes unavailable).
Action - Apply fertilizer at proper rate for plants. Try to apply fertilizer right at root system of plants. Have soil tested for PH and adjust as necessary to bring PH to proper level for the plants that are being grown.
Symptom - Can occur on indoor and outdoor plants. Edges of leaves may become scorched brown or completely black. Roots and foliage appear stunted. Sometimes a whitish crust will form on soil surface.
Causes - Excessive fertilizer salts in the soil (for indoor plants this may be caused by watering from the bottom). This can result from fertilizer applications being too frequent combined with not enough water, or fertilizing when the soil is dry. Mixing up fertilizer at too high of a concentration can cause salty injury as well.
Action - Take care to fertilize only when soil is moist. Mix fertilizers at proper rate as listed on label.
Leach salts from soil by watering three times and each time you water, water enough so that water comes out drainage hole.
Symptom - Surface of leaves have dead tan or brown patches. Leaf tissue may appear lighter or turn gray.
Causes - Light levels that are too high for plant or taking plants outdoors from low light conditions and placing them in direct sunlight.
Action - For indoor plants, move plants away from sunny windows or place a translucent blind or curtain across window. Acclimatize plants by bringing them outdoors to a shaded location for a few hours each day then gradually place them in brighter light.
Symptom - Otherwise known as white drupelet disorder. White or tan spots appear on individual drupelets on fruit.
Causes - Fruit exposed to hot, dry winds for extended periods of time.
Symptom - Tips may appear brown coloured or black coloured. Damage can extend to side margins of leaves.
Causes - Toxic compounds in irrigation water such as Chlorine, Fluoride, Boron. Very dry air. Plant drying out too much. Can occur from fertilizing when soil is too dry (see salt damage).
Action - Fertilize with fertilizer that contains calcium - the calcium will tie up Fluoride and Boron. Leave water to stand in open container for a few days to allow Chlorine to evaporate. Keep plants properly watered; when soil dries out an inch or two (for pots 6" or up) water thoroughly.