Cucumber Physiological Disorders

Cantaloupe Physiological

DisordersToT to FFS Staff By Mr. Allah Dad

KhanProvincial

Coordinator IPM KPK MINFAL

Air Pollution

symptoms• Another example of chemical

toxicity is damage from air pollutants. Several gaseous air pollutants can cause injury to plants, including ozone and sulfur dioxide. Ozone is produced when components of combustion/vehicle emissions such as hydrocarbons and nitrogen oxides react with oxygen and sunlight to form ground level ozone in the atmosphere. Its effects on plants can be mistaken for infectious diseases

Ozone Laayer

• Ozone can cause flecking which could be mistaken for mite injury. Ozone can also cause bronzing, chlorosis , and necrosis. Necrosis could be mistaken for a leaf spot caused by an infectious agent. In conifers, injury can include needle-banding and tip-burn Air pollution levels are often available from local

Soil Structure

• Soil structure determines the soil's ability to hold water, nutrients, and oxygen and make them available to plants. The most common issue related to soil structure is compaction, which results in inadequate pore space for root growth. Clay soils, with their smaller particle size, have naturally smaller pore space and are at high risk for becoming severely compacted. Compaction can occur from a variety of sources including traffic (particularly heavy farming or construction equipment) (Figure 1), raindrop impact, tilling operations (plow layer), and minimal crop rotation. Reduced water availability is an obvious consequence of compaction as runoff occurs more frequently in a compacted soil and available pore space to hold water is limited

• symptoms

SoilpH

• Soil pH below 5.5 generally results in low availability of calcium (Ca), magnesium (Mg), and phosphorus (P), and increased solubility of aluminum (Al), iron (Fe), and boron (B). High levels of these three nutrients in low soil pH are common, and can induce toxicity symptoms in plants. Soils with pH levels above 7.8 have a high availability of Ca and Mg at the expense of P, B, Fe, manganese (Mn), zinc (Zn), and copper (Cu). Plants grown in these alkaline soils often have deficiency symptoms to these nutrients

• symptoms

Attrazine Pesticides

Calcium Deficiencysymptoms

• Calcium is important for the functioning of cell membranes and the strength of cell walls. Most calcium-related disorders of crops are caused by unfavourable growing conditions and not by inadequate supply of calcium to the roots. Rapidly growing crops in hot windy conditions are most at risk. Deficiencies can also develop when cucumbers grow quickly under continuously humid conditions, as in a polyhouse. Other contributing factors are waterlogging, soil salinity, high potassium or ammonium supply, and root disease

Boron Deficiency symptoms

• Boron deficiency causes both leaf and fruit symptoms. The main leaf symptoms are a distortion of newer leaves (in severe cases the growing point dies) and the appearance of a broad yellow border at the margins of the oldest leaves. Young fruit can die or abort; abortion rates are high. The symptoms of boron deficiency on mature fruit are distinctive and include stunted development and mottled yellow longitudinal streaks, which develop into corky markings (scurfing) along the skin. These symptoms are often most severe near the blossom end of the fruit. Similar symptoms can occur on fruit grown in polyhouses with inadequate winter heating. Developing and mature fruit can taper and curve at the blossom end. The proportion of pith to seed is often higher in boron-deficient fruit.

Older leaves on boron deficient plantsdevelop a yellow border (top and left).New leaves are distorted and appearmottled

Chilling/frost injury

Excess Soil Moisture

The phosphorous deficient plant (on the left) is stunted and has small, dark green, dull leaves.

A healthy plant is on the right.

The oldest leaf of this stunted plant is bright yellow, but the leaf above it remains dark green.

Iron Deficiency Iron deficiency

• Iron is needed to produce chlorophyll and to activate several enzymes, especially those involved in photosynthesis and respiration. Deficiencies of iron are more likely in alkaline or calcareous soils, and can be induced by over-liming, poor drainage, or high concentrations of metallic ions in the soil or nutrient solution. Iron availability decreases at pHs above 7. Manganese toxicity can induce an iron deficiency

Magnesium deficiency

• Magnesium deficiency causes yellowing of older leaves. The symptom begins between the major veins, which retain a narrow green border. A light tan burn will develop in the yellow regions if the deficiency is severe. Fruit yields are reduced.

Yellowing and light tan burn on older leavesof magnesium deficient plant (left) compared witha healthy plant (right).

Manganese Deficiency symptoms

• The function of manganese in the plant is closely associated with the function of iron, copper and zinc as enzyme catalysts. Manganese is needed for photosynthesis, respiration and nitrate assimilation. Deficiencies are more likely in calcareous or alkaline soils, or over-limed soils; availability is high in acidic soils.

• The veins of middle to upper leaves of manganese-deficient plants appear green against the mottled pale green to yellow of the blade.

Molybdenum Deficiency

Nitrogen Deficiency

Symptoms• Most plants need nitrogen in large

amounts. It is generally considered to drive plant growth, probably because its supply is often limiting. A shortage of nitrogen reduces the plant's capacity to trap energy through photosynthesis. Nitrogen is required in the production of chlorophyll (the green pigment in leaves), which is responsible for converting sunlight to usable plant energy

Phosphorus Deficiency symptoms

• Phosphorus-deficient plants have weak roots, are stunted, and produce small, dark, dull, grey-green leaves. The oldest leaf, at the base of the shoot, turns bright yellow. However, unlike nitrogen deficiency, the leaf directly above this leaf remains dark green. Brown patches appear between the veins on mature leaves. These become scorched and spread until the leaf dies prematurely. Fruit set is reduced and so production is impaired.

The phosphorous deficient plant(on the left) is stunted and hassmall, dark green, dull leaves.A healthy plant is on the right.

Phosphorus Toxicicty

• Phosphorus toxicity Phosphorus toxicity is uncommon in soil-grown crops but can occur in hydroponic

Zinc Toxicity symptoms

• Zinc toxicity causes a pale green chlorosis of newer leaves. If toxicity is severe, pinhead-sized light-brown spots may appear between the veins. Older leaves may wilt and appear dull. All leaves are a lighter green than is normal

Where there is excess zinc, the older leaf (onthe left) appears dull. The younger leaf is palegreen with pinhole-sized light brown spotsbetween the veins

Potassium Deficiency

symptoms• Potassium deficiency causes yellowing and

scorching of older leaves. These symptoms begin at the margins of the leaf and spread between the veins towards its centre. Large areas of tissue around the major veins remain green until the disorder is well advanced. A brown scorch develops in the yellow areas and spreads until the leaf is dry and papery. As each leaf dies, others further up the shoot develop the same symptoms. These symptoms can develop rapidly in hot weather. Fruit may not expand fully at the stem end, although they look swollen at the tip end, a symptom that is also caused by water stress.

Salt Injury symptoms

• Plants grown under saline conditions, where the soil or growing medium has high electrical conductivity (EC), are stunted and produce dark green, dull, leathery leaves that are prone to wilting. A narrow band of yellow necrotic tissue is often present on leaf edges. This can affect leaf expansion, causing a slight downward cupping of the leaf. After a serious water stress, the oldest leaves may develop a uniform pale green chlorosis and small necrotic areas within the leaf. If water supply is maintained, leaves may only develop a band of pale green tissue around their edges. Plants are likely to wilt in warm weather

Wind and Sand Injury

Chloride Toxicity

symptoms

• Cucumbers are moderately sensitive to chloride. Chloride salts are common in the soil or groundwater in areas on Wianamatta Shale (for example, around Glenorie and Blacktown in NSW). Chloride is also present in fertilisers, such as muriate of potash (potassium chloride). Do not use these fertilisers if salt is a problem. Chloride toxicity reduces plant vigour and causes yellowing and scorching of leaf margins, and premature leaf fall

Band of pale green tissue around the leafmargin with some edge scorching associatedwith 3% chloride in tissue

2,4-d Pesticide Injury

Blossom End Rot

Drought Stress

Flood Damage

Hollow Heart