The Effects Pests and Diseases Have on Plant Growth?

1. The Effects Pests and Diseases Have on Plant Growth? Environmental Factors

2. Questions? What problems do diseases and insects cause plants? Why should we be concerned about the damages caused by pests on plants?

3. Disease and Insects on Plants Pests can injure plants in many ways. The damages can result in losses for the producers. Damage caused by pests consists of: • Holes in the leaves • Damage to the vascular tissue • Attack to the fruit • Contamination of the plant • Loss of nutrients • Damage to the land • Death of the plant How damage affects the producer: • Reduced yields • Lower quality • Increases production costs • Provides hiding places for other pests • Restricts marketing

4. Identifying the Affected plant • The first step in diagnosing a plant problem is identifying the plant that is affected. • Identifying the plant helps narrow the list of possible causes considerably. • A species will often have the same problem repeatedly. • With this knowledge, one can diagnose the problem given the plant name and symptoms.

5. Determining the cause of the problem • Once you identify the plant that is affected, then you can determine the cause. • Plant problems are caused by two conditions. • Biological (Biotic) • Environmental Conditions (Abiotic) • Biological – Organisms that include insects, rodents, and microorganisms, such as bacteria, viruses, and fungi. • Environmental Conditions – Include heat, drought, cold, etc…

6. Identifying the Affected plant • How can we determine if the problem is Biotic or Abiotic in origin? • Examine the plant closely because they both cause specific problems. • See if something is gained or something is missing. – Look for evidence that helps distinguish between the two. • Once the problem is discovered the necessary treatments can be taken

7. Biotic – living organisms • Damage to plants by insects and related pests is almost always from feeding in two ways: • Chewing • Sucking • Chewing – Pests such as larvae (caterpillars & grubs), grasshoppers, boring insects, snails and beetles. • These pests eat plant parts and become a major problem as they mature • Easy to identify – insects may be present or holes are found in leaves, stems and/or roots.

8. Biotic – living organisms • If chewing pests are suspected, inspect the plant to determine the insect causing the damage. • Under the leaves, near buds and feeding site, as well as the soil should be inspected. • Many pests are not present during day, so inspection should take place after dark.

9. Biotic – living organisms • Sucking – Pests that feed on the sap by inserting their mouthparts into the phloem or by feeding on sap from wounds. • Pests such as aphids, scales, mites, whiteflies, thrips, etc… • Diagnosis is more difficult • Usually small and varies in damage • Symptoms include puckering (cupping) or bleaching of the leaves.

10. Determine the cause of the problem CHEWING SUCKING • Caterpillar • Grubs/Bores • Leaf Miners • Grasshoppers • Beetles • Snails/Slugs • Earwigs • Aphids • Scale • Whiteflies • Mealybugs • Mites • Thrips

11. Biotic- Microorganisms • Another organism that damages the plants are microorganisms • Cause diseases that kill the foliage or rot the root system. • Divided into three types; • Fungi • Bacteria • Viruses

12. Biotic -Microorganisms • Fungi – single or multi-celled organism that lacks chlorophyll • Rely on sources for food and energy • Responsible for more plant diseases • Easy treated • Common Fungus diseases of plants • Mildew • Wilt • Rot • Leaf spot • Rust • Canker • Smut • Blight

13. Biotic -Microorganisms • Bacteria – single celled organism, usually lack chlorophyll, and grows in colonies • Spread by splashing water or contaminated tools • Responsible for few plant diseases • Difficult to treated • Viruses – not alive and not referred as microorganisms • Spread among plants by pests and hum • Viruses: • Stunt • Curly Top • Mosaic • Yellows

14. Abiotic – Environmental Conditions • Frost Damage - differs according to age and specie • Young tissue is more tender • Woody plants are more resistant • Symptom – overnight wilting (uppermost leaves and buds) • Winterkill – is the partial or total death due to cold temperatures. • Complete winterkill both tops and roots die • Manifest “burning” of evergreens – leaves turn brown, causing the tree to be marred.

15. Abiotic – Environmental Conditions • Drought – Occurs due to the lack of water • Wilting is the main symptom • Drought-struck plants will revive unless leaves are leathery and crisp • Many will regenerate from roots • Poor Drainage & Flooding – In which roots remain in water (saturated soil) • Plants die due to the lack of oxygen • Many will tolerate occasional flooding

16. Abiotic – Environmental Conditions • Lack of Soil Nutrients • Will not kill plants, but stunt and bleach • Symptoms vary with each specie –required amount of elements • 80% of deficiencies are lack nitrogen, phosphorous, and potassium. However, in Utah – potassium is readily deficient, due to our soil type.

17. Abiotic – Environmental Conditions • Unavailability of Nutrients – pH –Plants that are unable to absorb the essential elements due to high or low pH. • Iron and Manganese are the most effected by pH

18. Unavailability of Nutrients – pH

19. Abiotic – Environmental Conditions • Excess Soil Salt – An excess of a nutrient buildup in the soil • Wilting and browning will occur • Similar to signs of drought • Cured by leaching • Heat Scorch- Due to reflection of sun-generated heat from surfaces • Higher on south-facing walls • Leaf margins and veins turn brown • Tolerance varies among species

20. Abiotic – Environmental Conditions • Soil Compaction – the compacting of soil due to high traffic areas • Air space is compressed • Air & water absorption is inhibited • Slows plants grow – extreme cases plants may die

21. Abiotic – Environmental Conditions • Improperly Applied Chemicals – Injure to plants when chemicals are applied in excessive amounts or to the wrong specie. • 2, 4-D is the most frequent killer • Spray drift can also cause distorting and curling of the plant

22. Abiotic – Environmental Conditions • Grade Changes – Raising soil levels over roots more than a few inches. • Water and oxygen are restricted • Tree wells are necessary • Air Pollution – Problem in few areas • Affects susceptible plants – cone bearing evergreens • Damage occurs in many forms • Browning or death of foliage

23. Treating Plant Disorders • To restore a plant to its healthy state it depends on the condition (Abiotic or biotic). • Abiotic – Correct the condition or find a plant that will tolerate the situation • Biotic – Find plants that are not susceptible or keep plants healthy or use an integrated pest management approach. • IPM (Integrated Pest Management) • Identification (plant and pest) • Damage to plant (location) • Sanitation Control • Physical/Cultural Control • Biological Control • Chemical Control • The basis of an IPM program is to predict the problem and formulate a control plan.

24. Integrated Pest Management • The current, most widely accepted approach to pest management is integrated pest management (IPM). • Pests are recognized as a part of the crop ecosystem. • The goal is to reduce damage to a low level. • Below the economic threshold, above which injurycannot be tolerated and controls must be used. • When this action threshold of damage is reached, control measures are taken.

25. Integrated Pest Management • While difficult for a gardener to be familiar with the life cycles of all the insects and diseases of plants, he/she can use integrated pest management to a limited extent: • Decide whether it is due to an insect, disease, rodent, nutritional deficiency, or other source. • Determine whether the harm being done is sufficientto justify control—set a level of tolerable damage. • Treatment might not be justified at all. • Use cultural/biological controls, if practical &available. • Apply a pesticide as a last resort, or if the only available control.

26. Integrated Pest Management • Identification (plant & pest) - Before deciding to take any control action, you must correctly identify the plant infected and the pest causing harm. • Learn pest and host life cycle, anatomy, biology, color, shape, mouthpart (chewing or sucking), and size. Often, other stages of the life cycle are susceptible to preventative actions. • Life cycle: The way the pest develop, grow and change. • Complete Metamorphosis • Incomplete Metamorphosis

27. Integrated Pest Management • Complete Metamorphosis – Has four changes of growth and development. • Egg • Larvae • Pupa • Adult • Knowing what to look for can help identify the insect

28. Integrated Pest Management • Incomplete Metamorphosis – Has three stages of growth and development. • Egg • Nymph • Adult

29. Integrated Pest Management • Damage (location) – To identify the location of the damaged tissue can help narrow the pest. • Damage parts: • Leaves (top and bottom) • Roots • Stems • Buds • Fruit • This will help again indentify the pest as a chewing, sucking or disease.

30. Integrated Pest Management • Sanitation – Involves removing diseased plant material or harboring plant material. • Reduces the pest population • Weeds and leaves should be removed

31. Integrated Pest Management • Physical Control – Method that physically prevents activity of pests and diseases. • Pruning – A control technique to control localized diseases – gall, wilt, canker, and blight • Rouging – Removing diseased plants to stop spreading. • Valuable for annuals • Controls only viruses and bacteria • Crop Rotation – Planting a different specie in an area each year • Valuable control for soil-pathogens

32. Integrated Pest Management physical control – continued…. • Planting Resistant Species – One of the best control methods • Many plants have resistance to diseases • Plant Selection and Culture – Selection of plants that are not generally affected by diseases, as well as are adaptable to the climate (environment)

33. Integrated Pest Management • Biological Control - Involves the use of beneficial living organisms to control pests (Microbial, parasitic, or predators organisms). • Advantages: • Considered environmentally safe – no use of chemicals • Does not create new pest problems • Pest cannot develop resistance • Disadvantages: • Very narrow host range • Process is slow • Does not eradicate pest • Expensive and requires supervision

34. Integrated Pest Management • Chemical Control - methods involve the use of chemicals such as poisons, growth regulators, sterilants, and attractants and repellants to control pests. • Used when all other factors are useless • Should be specific to the pest • Used when outbreaks are severe • Chemical controls: • Insecticides • Miticides • Fungicide • Bactericide • Herbicide • Pesticides

35. Integrated Pest Management chemical control, continued… • There are various chemical control methods. • Sprays – kill on contact or are absorbed • Soil Drenches – Contact or systemic underground • Systemic – absorbed in the plant and kill pest that feed on the plant • Baits – Stomach poisons • Repellants – products applied to plant to repel insect.

36. Choosing Chemical Controls • Select chemicals that will control pests satisfactorily. As nontoxic as possible to people & beneficial organisms.

37. Choosing chemical control • Table 7-4 lists the LD50 of many common insecticides, fungicides, and bactericides. • The “lethal dose killing 50% of a population.” • Expressed in milligrams per kilogram of total body weight. • Pesticides with different modes of action shouldbe rotated to avoid resistance. • The mode of action is the way it kills the pest. • Rotating between insecticides with different modesof action, resistance development is slowed & betterpest management results are obtained.

38. Safe use of Chemical Controls • Rules to observe: • Use chemical only when needed. • Select the least toxic • Read the label carefully • Wear protective clothing when mixing and applying chemicals • Apply when weather is good (not to hot or windy) • Apply the amount specified • Apply complete coverage • Use good conditioned and appropriate equipment • Dispose of chemical properly • Label holding tank and treated crops with the name of the chemical used.

39. Safe use of Chemical Controls