Identifying and Controlling Plant Disorders Insects and Pests

Identifying and Controlling Plant Disorders Insects and Pests

Snails Solution: • Sluggo • Metaldehyde

Slugs Solution: • Metadehyde • Bug-Geta • Sluggo • Escar-Go

Whitefly Solutions: • Insecticidal soap • Permethrin dust • Deltmethrin dust • Bifen

Aphids Solutions: • Deltamethrin dust • Permethrin dust • Permethrin concentrate • Cyonararts • Cyfluthrin • Bifen

Fungus Gnats Solutions:

Shore Flies Solutions:

Thrips Solutions:

Leaf Miner Solutions: • Neem • acephate (Orthene) • imidacloprid

Spider Mites Solutions: • Orthene, certain Isotox formulations which contain acephate. • Talstar which contains bifenthrin • • Insecicidal soaps Sulfur dust

Mealy Bugs Solutions: • A mix of water, alcohol, and soap • Dycarb 76 WP and Turcam 76 WP which contains bendiocarb • Talstar which contains bifenthrin • Dura. Guard which contains chlorpyrifos • Decathlon which contains cyfluthrin

Leaf Hopper Solutions: • chlorpyrifos (Lorsban 4 E) • beta-cyfluthrin (Baythroid XL) • dimethoate (Dimethoate 4 EC) • lambdacyhalothrin (Lambda-Cy 1 EC) • lambdacyhalothrin (Warrior II)

Spittlebug Solutions: • Bifen • carbaryl (Sevin)

Scale Solutions: • paraffinic oil (Horticultural Oil) • insecticidal soap (Safer's Soap) • chlorpyrifos (Dursban) • carbaryl (Sevin) • acephate (Orthene) • malathion (Malathion)

Identifying and Controlling Plant Disorders Diseases

Powdery Mildew • Problem: Powdery mildew appears as a dusty white to gray coating over leaf surfaces or other plant parts ( In most cases this fungal growth can be partially removed by rubbing the leaves. Powdery mildew, however, will begin as discrete, usually circular, powdery white spots. As these spots expand they will coalesce, producing a continuous matt of mildew (similar to dirt or dust). A plant pathologist using a microscope can determine whether a fungus is present anytime the whitish patches are present. • Solution: For indoor plants, disease management includes gathering up and destroying fallen leaves, reducing relative humidity around plants, and spraying with a fungicide. Some products that may be used to treat powdery mildew on indoor plants include: potassium bicarbonate (Greencure), Bacillus subtilis (Serenade Garden RTU* or Plant Guardian Biofungicide), and some products containing the active ingredient neem oil.

Leaf Spot • • Problem: BACTERIAL. Water-soaked spots which spread rapidly to the rest of the leaf under wet conditions. Solution: Remove diseased leaves and spray with Streptomycin at 200 ppm. Follow all mixing instructions.

Root rot • • Problem: It is a soil-borne and root infection is favored by saturated soil moisture. As the infection spreads, roots collapse and decay. Early above-ground symptoms include yellowing of leaves with some burning of the margins and lack of new growth. As the disease progresses, terminal leaves become small, and excessive defoliation occurs because of severely damaged roots. Solution: If it is still early, damaged roots can be removed and the plant should be repotted and drainage should be improved. Once all roots are rotted there is no treatment. Using soil that not only retains moisture but also has good drainage can prevent root rot. Not overwatering also prevents root rot.

Stem Rot • Problem: Brown stem rot is caused by the fungus Phialophora gregata. The fungus survives in plant residue on which spores are produced from precolonized woody stem tissue. Infected plant residue is thought to be the main source of spread for the fungus. Infections occur through the roots and lower stem early in the season and the mycelium grows upward in the water-conducting xylem vessels. Water and nutrient flow is thus inhibited because the mycelium plugs the xylem vessels. • Solution: When a stem 'wilts' it should be severed across the green part of the stem below the dead area of the stem. This is invariably low down on the stem. Thus cut the stem just above soil level if the whole stem is involved. The end of the stem left in the ground will show its green face to you and you will know that the lesion is above this level. The lesion can be identified using one of two ways after placing the stem lengthways on a table: 1. Chip away with a sharp knife at each node starting at the bottom node of the stem. If wilt is present you will quickly see the black area in one node. Below that node the stem is green, at the affected node it is black and the stem is brown above. 2. With care and using a sharp knife or razor blade knife it is possible to start at the bottom of the stem and slice up the middle of the stem dividing it into two parts. Sharp scissors will also do this work. As you start up the stem you will be in green tissue, at the affected area this gives way to the characteristic black lesion and above is the brown dying stem.

Botrytis – Gray mold • Problem: • Solution:

Downy Mildew • Problem: • Solution:

Tospovirus (INSV and TSWV) • Problem: • Solution:

Pictures

Rust • • Problem: this appears as raised, round rust colored spots on the underside of leaves. Solution: Hygiene is the best way to prevent rust - ensure all fallen leaves are removed from the top of the soil before they begin to decompose. Prune the plants to ensure a free circulation of air, especially at the centre. Remove and burn all infected leaves from the plant. As soon as rust is noticed, remove all affected leaves and burn them. Try to isolate infected plants from healthy ones. The infection spreads through the air via spores. The conditions needed for rust are wet leaves at the right temperature. The plants should be sprayed with a fungicide such as thiram, maneb or zineb at ten day intervals.

Damping-Off • • • Problem: The single term used to describe underground, soil line, or crown rots of seedlings due to unknown causes is damping-off. The term actually covers several soil borne diseases of plants and seed borne fungi. Rhizoctonia root rot (Rhizoctonia solani) is a fungal disease which causes damping-off of seedlings and foot rot of cuttings. Infection occurs in warm to hot temperatures and moderate moisture levels. The fungi is found in all natural soils and can survive indefinitely. Infected plants often have slightly sunken lesions on the stem at or below the soil line. Transfer of the fungi to the germination room or greenhouse is easily accomplished by using outdoor gardening tools inside or vice versa. The germination room should not be used for mixing potting soils or transplanting seedlings as a general rule. Pythium Root Rot (Pythium spp. ) is similar to Rhizoctonia in that it causes damping-off of seedlings and foot rot of cuttings. However, infection occurs in cool, wet, poorly-drained soils, and by overwatering. Infection results in wet odorless rots. When severe, the lower portion of the stem can become slimy and black. Usually, the soft to slimy rotted outer portion of the root can be easily separated from the inner core. Species of Pythium can survive for several years in soil and plant refuse. Phytophthora root rot (Phytophthora spp. ) are usually associated with root rots of established plants but are also involved in damping-off. These species enter the root tips and cause a water-soaked brown to black rot similar to Pythium. These fungi survive indefinitely in soil and plant debris. Black root rot (Thielaviopsis basicola) is a problem of established plants. It does not occur in strongly acid soils with a p. H of 4. 5 to 5. 5. It usually infects the lateral roots where they just emerge from the taproot. The diseased area turns dark brown, and is quite dry. The fungi survive for 10 years or more in soil. Seeds may be infected as soon as moisture penetrates the seed coat or a bit later as the radicle begins to extend, all of which rot immediately under the soil surface (pre-emergence damping-off). This condition results in a poor, uneven stand of seedlings, often confused with low seed viability. Cotyledons may break the soil surface only to whither and die or healthy looking seedlings may suddenly fall over (post-emergence damping-off). Infection results in lesions at or below the soil line. The seedling will discolor or wilt suddenly, or simply collapse and die. Weak seedlings are especially susceptible to attack by one or more fungi when growing conditions are only slightly unfavorable.

Damping-Off (con’t) • • • • Solution: Purchase disease free plants and seeds. Know your supplier. Do not be afraid of fungicidal coatings on seeds which will be direct sown out doors in cold soils, such as corn and peas. Seed borne disease can also be avoided by soaking the seeds for 15 minutes in a bleach soak (one teaspoon per quart of water) prior to sowing. Use sterile well drained soil mediums. Plants must not have their crowns below the soil line. Seeds must not be covered more than 4 times the thickness of the seed. Use plant containers with drainage holes, water from the bottom only, and avoid excess watering. Do not allow pots to stand in water as excess water cannot drain and the roots will be starved for oxygen bringing all growth to a halt. Avoid overcrowding and overfeeding of plants. It is important to maintain constant levels of growth through proper lighting and complete control of the growing environment. Avoid working with plants (taking cuttings or transplanting) when the soil is wet. Do not use water from ditches or drainage ponds or rain barrels in the germination room. Avoid spreading soil from infested areas or tools which have been used out of doors. Disinfect tools and containers with one part bleach in four parts water or with 70 percent rubbing alcohol (isopropyl). Captan (sold as Captan) controls most pathogens, but not Rhizoctonia. Metalaxyl (sold as Subdue or Apron) controls Pythium, Phytophthora, and Aphanomyces. Iprodione (sold as Chipco) controls most pathogens, but not Pythium, Phytophthora, or Aphanomyces. Etridiazole and Thiophanate-methyl (sold as Banrot) controls most all pathogens. PCNB-etridiazole (sold as SA-Terraclor or Super-X) good general purpose fungicide. PCNB-quintozene (sold as Terraclor, Fungi-clor, or PCNB) controls Rhizoctonia and Sclerotinia species. Fosetyl-A 1 (sold as Aliette) controls Pythium, Phytophthora, & Aphanomyces.

Bacterial Wilt • • Problem: This disease occurs in scattered plants or groups of plants. The initial symptom is wilting of terminal leaves, followed in 2 -3 days by a sudden and permanent wilt. Adventitious roots may develop on the main stems. Additional symptoms include vascular browning, water soaking of pith followed by browning, and in later stages browning of cortex near the soil line. Bacteria streaming can be seen when a freshly cut stem is suspended in water. Solution: Once a plant is infected with bacterial wilt, no control of the pathogen is possible. Infected plants should be removed and destroyed without injuring nearby plants. The best control for this disease is achieved by managing the beetle vector of the pathogen

FLORICULTURE CDE Identifying and Controlling Plant Disorders

Nutritional and Environmental Disorders

Poor soil drainage • • Problem: Garden soil may appear ideal for potting indoor plants but actually causes problems. This soil may be wonderful for outdoor gardening under natural conditions, but after a few months the garden soil becomes hard and almost rock-like in a plant pot. Plants in garden soil grow satisfactorily for a month or two, but soon the lower leaves turn yellow and the plants become unthrifty. This problem is the result of poor drainage and the lack of soil aeration due to improper soil structure. Most garden soils become compacted with time and house plants grow poorly in compacted soil. Solution: A proper soil mixture is of utmost importance to a house plant because the roots are restricted by the pot. A good potting soil should have the capacity to retain some air and moisture and yet drain well and hold nutrients. Sand or perlite added to the soil will improve aeration and drainage. Clay or organic matter will help retain water. Organic matter, plus commercial fertilizers, will maintain adequate nutrient levels. Modern "soilless" potting medias do not contain soil so the addition of fertilizer is required to provide all essential plant nutrients.

Pictures of poor drainage

Overwatering • Problem: Plants that have been over watered often have similar signs to plants that have been under watered. An over watered plant will be droopy, wilty looking, with leaves hanging as if weighed down. The roots of the plant are drowning; unable to breathe air that they need to support the plant. The roots become weak and start to rot. • Solution: When the soil or the compost has become too wet or saturated, the leaves of the plant will become limp. Disease can over take a plant quickly when it is in this vulnerable state. The lower portions of the plant are the first to become infected, so you might have to cut a few leaves off if you find this happening to your plant. For the plant that has become too wet and moist, take the plant and soil out of the container in which it was sitting. Hold the plant firmly in your hand so it will not break or be damaged while you are working with it. A plant with lots of roots will retain the shape of the container when you first pull it out. The next step is fairly easy, you are going to take a few paper towels and set the plant on them. Allow some of the excess water to drain out of the soil and into the paper towel. Pat down the soil to bring more water out. Check the roots for fungus, bacteria or worms that may be taking over in the soil. Leave this over watered plant to sit out on a few fresh paper towels over night. Excess water will continue to drain out of the soil and the roots will have a better chance of getting the air that it needs for reviving itself. After a day, or at least twelve hours, you can put the plant back into the container. Add a little fresh soil if need be around the edges and the top of the plant. Allow the plant to dry out normally before watering once again. • •

Overwatering Pics

Too little water • Problem: Droopy plants, leaves falling off, shriveled up, light colored soil • Solution: Soak in water until it perks up then water regularly. Cut off any completely damaged foliage

Improper Temperature • • Problem: Sudden loss of leaves is frequently caused by a rapid temperature change. It may also be caused by such factors as prolonged hot or cold drafts, dry air, exposure to gas or furnace fumes or by changing the location of the plant from a sunny to a dark location. Solution: Move plant away from all these factors.

Cold Temperature/Freeze • Problem: • Solution:

Cold Water Damage Problem: Solution:

Nitrogen deficiency • • Problem: Nitrogen (N) deficiency in plants can occur when woody material such as sawdust is added to the soil. Soil organisms will utilize any nitrogen in order to break this down, thus making it temporarily unavailable to growing plants. It is more likely on light soils and those low in organic matter content, although all soils are susceptible. Cold weather, especially early in the season, can also cause a temporary shortage Symptoms include poor plant growth, leaves are pale green or yellow in the case of bracs. Lower leaves show symptoms first. Leaves in this state are said to be etiolated with reduced chlorophyll. Flowering and fruiting may be delayed. Solution: Prevention and control of nitrogen deficiency can be achieved in the short term by using grass mowings as a mulch, or foliar feeding with manure, and in the longer term by building up levels of organic matter in the soil. Sowing green manure crops such as grazing rye to cover soil over the winter will help to prevent nitrogen leaching

Iron Deficiency • • Problem: A deficiency in the soil is rare but iron can be unavailable for absorption if soil p. H is not between about 5 and 6. 5 A common problem is when the soil is too alkaline (the p. H is above 6. 5). Also, iron deficiency can develop if the soil is too waterlogged or has been overfertilised. Elements like calcium, zinc, manganese, phosphorus, or copper can tie up iron if they are present in high amounts. Iron is needed to produce chlorophyll, hence its deficiency causes chlorosis. Symptoms include leaves turning yellow or brown in the margins between the veins which may remain green, while young leaves may appear to be bleached. Fruit would be of poor quality and quantity. Solution: Iron deficiency can be avoided by choosing appropriate soil for the growing conditions. Plants should be kept far away from cement. Iron sulfate or sulfur can be added to acidify the soil

Phosphorous deficiency • • Problem: Phosphorus (P) deficiency is a plant disorder that is most common in areas of high rainfall, especially on acid, clay or poor chalk soils. Cold weather can cause a temporary deficiency. All plants may be affected, although this is an uncommon disorder. Symptoms include poor growth, and leaves that turn blue/green but not yellow—oldest leaves are affected first. Fruits are small and acid tasting. Phosphorus deficiency may be confused with nitrogen deficiency. Undersides of tomato plant leaves, and the veins and stems, may turn purple. Solution: It can be controlled by applying organic sources of phosphorus such as rock phosphate or a high-phosphorus fish fertilizer applied as a soil drench or foliar feed.

Ethylene Damage • Problem: • Solution: