Green Leaf HopperSignificance:Primarily a problem in the spread of Tungro disease.Growth stages when a problem:Seeding to panicle initation (1-4)Damage symptoms:Tungro (plants virus) causes stunting, reduced tillering, leaves light yellow.IPM levels: 5 per hillLife cycle: 23-30 days.Mechanism of damage: Virus spread or direct suckingControl:Control generally not required (Required in Tungro-prone area)Cypermethrin(USTAAD 10% EC 1 Lt/Ha)
Calsium (Ca) is taken up by plants as the calcium ion (Ca++). A structural nutrient, it is an essential part in cell walls & membranes & is required for the formation of new cells.
For this reason, early season availability of supplemental Calcium has a distinct effect on fruit set. Once deposited in plant tissues, Calcium is not remobilized. Therefore, young tissue is affected first under conditions of deficiency. Since Calcium is not mobile, the requirements of a crop for Ca++ after early fruit set are commonly supplied in the form of nutritional sprays.
Symptoms of K Deficiency:
• “Tip burn” of young leaves-celery, lettuce, Cabbge.
• Death of growing points (Terminal buds). Root tips also affected.
• Abnormal dark green appearance of foliage.
• Premature shedding of blossoms & buds.
• Weakened stems.
• Water-soaked, discoloured areas on fruit-blossom-end rot of tomatoes, peppers & melons; bitter pit or cork spot of apples & pears.
Potassium (K) is taken up by plants in the form of potassium ions(K+). It remains in ionic form within cells & tissues. Potassium is essential for translocation of sugars & for formation of Starch. It is required in the opening & closing of Stomata by guard sells. Potassium promotes root growth; produces larger, more uniformly distributed xylem vessels through the root system; & increases plant resistance to disease. Potassium increases size & quality of fruits, nuts & vegetables & improves winter hardiness of perennials. Plantsthat produce large amounts of carbohydrates have a high potassium requirements.
Symptoms of KDeficiency:
• Slow growth.
• Tip & marginal chlorosis.
• Weak stems & Stalks.
• Small fruit or Shriveled seeds.
Remedy: Apply potassium Fertilizer.
Phosphorous(P) is taken up by plants as ortho-phosphate PO42- .Phosphorous is present in all living cells. It is utilized by the plant to form nucleic acids (DNA & RNA). Through energy-rich linkages (ATP & ADP), it is involved in the storage & transfer of chemical energy used for growth & reproduction. Phosphorous stimulates seedling development & root formation. It hastens matuarity& promotes seed production.
Phosphorous supplementation is required most by plants under the following circumstances:
1. Cold water
2. Limited root growth period & rapid vegetative growth.
Symptoms of P Deficiency:
• Slow growth; stunted plants.
• Purplish coloration on foliage of some plants (Older leaves first).
• Dark green coloration.
• Delayed maturity.
• Poor fruit or seed development.
Nitrogen(N) is taken up by plants nitrate (NO3-) or ammonium (NH4+) ions. It is utilized by plants to synthesize amino acids, the building blocks of proteins.
The protoplasm of all living cells contains protein. Nitrogen is also required by plants for other vital compounds, such as chlorophyll, nucleic acids & enzymes. Chlorosis is usually more pronounced in older tissue. Since nitrogen is mobile within plants, it tends to move from older to younger tissue when in short supply.
Symptoms of N Deficiency:
• Slow growth; stunted plants.
• Yellow-Green colour (Chlorosis).
• Death(necrosis) of tips & margins of leaves, beginning with more mature leaves.
Remedy: Apply Nitrogenous Fertiliser.
Molybdenum (Mo) is taken up by plants as the molybdateion(MoO42-). It is required by plants for the utilization of nitrogen. Nitrate nitrogen is converted to amino acids by the nitrate reductase enzyme; this enzyme requires molybdenum. In addition, molybdenum is required for the symbiotic fixation of Nitrogen by legumes.
Symptoms of Mo Deficiency:
• Stunting & lack of vigor. This is similar to nitrogen deficiency, because of the key role of molybdenum in nitrogen utilization.
• Marginal scorching & cupping or rolling of leaves.
• “Whiptail” of Cauliflower.
• Yellow spotting of Citrus.
Boron(B) is predominately in solution as boric acid, H3BO3, and is taken up by plants in this form.It functions in the differentiation of meristematic of meristematic cells. Boron is also involved in regulating metabolism of carbohydrates in plants. Nearly all fruiting crops have a high demand for boron in the early fruiting stage. Foliar applications are an effective way to meet this demand at this critical growth state. Recent research has shown that boron is effective in increasing pollen viability, thus controlling to increased fruit set. When boron is deficient, cells may continue to divide, but structural components are not differentiated.
Symptoms of B Deficiency:
• Death of terminal growth, causing lateral buds to develop, producing a “witch’s broom” effect.
• Thickened, curled, wilted &chlorotic leaves.
• Soft or necrotic spots in fruit or tubers.
• Reduced flowering or improper pollination.
Plant uptake of copper is in the ionic form (Cu2+). Copper serves as an activator of numerous plant enzymes & plays a role in the development of plant pigments that influence colour. A copper deficiency interferes with protein synthesis. Copper deficiency has been observed on trees and vines growing on organic soils & sands.
Symptoms of Cu Deficiency:
Dieback of terminal shoots in trees.
Wilting & eventual death of leaf tips.
Formation of gum pockets around central pith in oranges.
Manganese (Mn) uptake is in the form of the ion Mn+2. Manganese serves as an activator for enzymes in plant growth processes. It assists iron in chlorophyll formation. High concentrations of manganese in plants may induce iron deficiency. Manganese is generally required with Zinc in foliar spraying of Commercial citrus. Other tree crops may show deficiencies.
Symptoms of Mn Deficiency:
Interveinalchlorosis of young leaves.
Gradation of pale-green leaf coloration, with darker color next to veins.
No sharp colour distinction between veins & inter veinal areas as with iron deficiency.