30/05/2013 - Disease and Disorder 27208

Today the class was with Ms.Lisa Burton starts at 11.00 - 12.00pm and 1.00pm to 3.00pm.

The topic that she thought us was on Bacteria. Bacteria are very small one-celled plants. It like fungi they lack chlorophyll. Most bacteria are Saprophytes which are useful as they break down organic matter. Only a few bacteria are plant parasites. All the plant parasitic bacteria are facultative saprophytes. Bacteria cells about 0.001 mm long. It a great diversity in shape and flagella (tails).

How bacteria cause disease

It is small size allows bacteria to easily invade plant tissue via natural openings and. wounds. Aerial bacteria which infects plants through recent wounds, lenticels, stomata and fresh abscissions. Soil bacteria which infects roots or crowns, enter via small wounds caused by cultivation. Bacteria can easily infect young tissue, therefore seedlings and fresh growth are at risk.

How bacteria spread

Reproduction is by asexual cell division called fission. In favourable warm moist conditions the cell grow quickly and divide. Aerial bacteria form colonies inside infected plants, producing a slime which comes from the plant in wet weather and is spread by rain splashes, irrigation water insects and dirty tools. Soil bacteria are spread in surface water run-off, dirty tools and machinery. They can swim short distances in soil water. Bacteria infect the developing seed.

How bacteria survive

All plants-disease bacteria become inactive in dry conditions. Remain protected but inactive inside disease tissue, however will die if removed from the host plants. Soil-living disease bacteria live as saprophytes in absence of host plant and can last for many years.

Symptoms the pathogens concerned may cause completely different symptoms on other host plants. In many cases a similar symptoms on a different host is caused by a different pathogens.

Crown Galls - Abnormal swellings or outgrowths on a plant. The infested roots and crown develop large, rough galls. The roots and crown grow poorly which equal to stunned growth, reduced yield. Other parts of plants may show galls too.

Cankers and dieback - This disease areas are on the stems. Often have bacteria ooze. Plants dies above if canker girdles stem which equal to dieback. For example are blast and fireblight.

Leaf and fruit spots - They have various pattern and colours. Bacterial spot often look oily and may have a pale halo. As the tissue dies in spots it falls out giving a shortgun appearance. 

Rots -  This cause of the plant to decay. Water soaked appearance. and give leaves a shot hole appearances.

Controlling bacteria 

• Control measures are different for soil borne and aerial bacteria.
• Timing is critical - lifecycle. 
• Bacteria diseased are difficult to control ad usually require a combination methods.
• Mostly bactericides are protectant, bactericides are not systemic.
• Fungicides have little effect  on bacteria with exception of copper-based sprays
• use resistant cultivar
• Plant only disease- free plants
• Use disinfected seed
• Disinfect the soil
• Use good crop hygiene practices
• Use careful growing practices, regular watering, feeding, care when cultivating

Viruses 

 

It a very tiny particles that can only be seen under an electron microscope. All are parasitic and cause diseases in plants and animals. 

How Viruses Cause Disease :

- Viruses interfere with the plants essential growth processes and energy systems.

- The virus particle cannot reproduce itself so it tricks the plant into making many more.

- The host cells use a lot of energy to reproduce the virus and the plant begins to loose vigour.

How Viruses Spread : 

- Within the plant

- Carried from cell to cell in the cytoplasm through tiny tubes called plasmodesmata (very slow)

- through the plants sap stream in the phloem (rapid)

Between plants 

- Must remain in plant sap, cannot spread on its own

- Wounds caused by pests, pathogens or environment

Viruses are difficult to control because they are not cellular, therefore we cannot use pesticides, as they are designed to disrupt the cellular organisation and they are protected inside the plant.

How do we prevent infection?

- keep viruses out of NZ by border controls

- Control insect vectors

- remove diseased plants

- Hygiene

- Propagate from virus free stock

- grow from seed and viruses don't normally spread to seed

- Use resistant tolerant cultivars

Symptoms of viral infections :

Mosaics - most common symptom, mottled light or dark green. Mottling may be in a defined pattern. In monocotyledons the mottling may occur as streaks along the veins.

Ring spots - These are chlorotic or necrotic rings which occur on leaves and sometimes the fruit and stems.

Chlorosis - They are yellowing of the green tissue due to a loss of chlorophyll. May appear as spots, inter-veinal spots and often about the leaf margins.

Necrosis - The spots of cells die with in the leaf, these may fall out giving a shot hole appearance. They can also show as streaks on the stems.

Distortion of leaves and fruits - The narrowing, rolling or crinkling of the leaf. The suppression of leaflets. Fruits misshapen and often have a crinkled surface.

Disorders - Plant disorders are typically caused by the following three factors such as unfavourable climatic conditions, nutrient deficiencies or toxicities and poor management.

1] Plant disorder due to climate such as light which is lack of light can cause poor growth and weak looking plants, typically etiolated, or stretched. Intense sunlight can cause sunburn in some plants and fruits.

Plants disorders or physiological disorders are the response by plants to unfavourable conditions caused by abiotic (non living) factors. No pathogen is involved in plant disorders.

Many crops have been severely damaged where poor interpretation has occurred, and incorrect treatments applied, particularly with nutrients disorders.

Temperature which are high can cause necrotic or dead patches on leaves. Low temperature can cause freezing and result in a range of damage symptoms including black burnt looking shoots, ring pattern on fruit and death of flowers. Extremely low temperatures can caused vertical cracking of bark on some trees. Russet is also a common damage.

Hail can obviously can cause tearing and bark damage, pitting of fruits and flowers. A risk of disease infection can follow hail.

Wind the symptoms is to damage can also vary from tattered leaves, wilted stressed plants, bruised fruits and flowers, wind rock and root damage.

Water excess and storage too much can result in wilt, dieback from the tips and the associated diseases of wet soils. The death of roots will cause drought-like symptoms such as dieback. Cracked fruits can result from over watering. A lack of water will result in wilt, shoot dieback, premature leaf-fall and eventual death.

2] Plant disorder due to nutrients and it always advisable to take leaf samples as a routine horticulture operations. It is highly recommended that you consider leaf sampling where nutrient issues are considered the problem.

• Nitrogen deficiency
• Phosphorous deficiency
• Potassium deficiency
• Sulphur deficiency
• Calcium deficiency
• Magnesium deficiency
• Zinc deficiency
• Manganese deficiency
• Boron deficiency
• Iron deficiency
• Copper deficiency

3] Plant disorders due to poor management and there are literally dozens of disorders that could result form poor management, and one could argue that poor climate management and nutrient status is also a management issue. For the purpose of this project we have tried to isolate climate and nutrients separately from the other management problems that can result.

Ms. Lisa Burton was reminding all students that there will be a test on disease on 13 June, 2013 and a assessment

29/05/2013 - Plant Identification Unit 20574

On 29/05/2013 there is no morning class on Plant Collection Gardening on Unit  21026 because the ground is too wet due to heavy snow on 28/05/2013.

In the afternoon we had Plant Identification class on Unit 20574 with Ms. Lisa Short. The topic she discuss with us was  Weeds in  New Zealand.

Weed Control can be someone favourite plant or flower maybe daisies for example - but some who has a green type of lawn, loathe them. Many describe weeds as an unwanted plants growing in wrong place, if it grow quickly and is hard to control then it's weed.

Perennials are plants that come up each season and may die down over the winter months. Some perennials plants can look like some common types of weeds.

Weeds can be split into many categories but I find it easy to divide them into two sections - Annuals and Perennials. Annual weeds in general spread by seed. Perennial weeds are weeds that live for more than one season - this means that they do not die after one season, some perennial weeds may die down over the cooler month but adorn themselves with fresh healthy new green leaves.

How do weeds get to New Zealand?

- 74% were introduced as ornamental (garden) plants

- 14% were introduced for agriculture, horticulture and forestry

- only 10% were accidentally introduced

- 2% others

Weeds are useful to some people for soil stabilisation for reduce erosion, habitat and food for wildlife, nectar and pollen for honeybees and human consumption, medicine, building materials craft-making.

Weeds Characteristics

The top four weekly characteristics to remember are

• weeds produce many seeds and can reproduce vegetatively
• weeds grab all the nutrients and water
• weeds germinate and grow faster than native plants
• weeds avoid damage from natural enemies
• weeds have physiological adaptations such as fast uptake of nutrients
• weeds are tolerant of a variety of soil and climatic conditions (hardy generalists - can live almost anywhere)

Apart from that we went to Dunedin garden to see the samples of weeds which are required and samples of native trees for workbook.                                                                                                                                                         

Sample that we identify are Euphorbia peplus (Family Name : Euphorbbiaceae)

                                            Vicia sativa (Family Name : Fabaceeae)

                                            Lamium purpureum (Family Name : Lamiaceae)

                                            Epilobium ciliatum (Family Name : Onagraceae)

                                            Piantago lanceolata (Family Name : Rumiaceae)

                                            Solanum nigrum (Family Name : Solanaceae)

                                            Urtica urens (Family Name : Urtiaceae)

                                                                                                                                             

Today the weather in the afternoon isa sunny day with 11 degree Celcius. Wind is light winds.Rainfall 0.00mm. Humidity 58%. Pressure N/A

23/05/2013 - Diseases and Disorders Unit 27208

My class was with Ms.Lisa Burton at 1pm. The topic that she thought us was Plant Diseases caused by micro-organisms that can live on, or inside, our plants causing damage to them. the three main types of micro-organisms are fungi, bacteria and viruses. 

Physiological Disorder that when any environmental factor is affecting plant growth in a negative way. For example climate factors may be too much sun, frost soil factors due to lack of nutrients. 

All living organisms require energy to grow, including micro-organisms. They gain this energy from consuming other organisms such as plants. Some are parasites - they feed on living tissue. Some are saprophytes which they feed on dead tissues. 

Which type of micro-organism do we want and why? When a parasite lives on a plant it effects the growth of the plant. 

Which type of micro-organism do we not want and why? When the parasites lives on a plant it effects the growth of the plant. When the parasite causes distinct disease symptoms we call the parasite a pathogen. 

A pathogen is a general term for an organism capable or causing death. The sign are any part of the pathogen we can see e.g. the body of the organism itself. The symptoms are plant reaction to being attacked by a pathogen @yellowing.

Causes of Diseases - the caused by bacteria, fungi and viruses. Fungi cause the greatest number of diseases. Diseases mainly occur when a pathogen alters one or more of the plants internal processes. This will result in the plant displaying various symptoms and / or displaying visible signs of the disease. 

Ms. Lisa taught us on Fungi. What is Fungi? Fungi are very small organisms which are often only visible through a microscope. Fungi are either parasites or saprophytes, so they can not make their own food, and therefore do not contain chlorophyll, the green pigment in other plants.

Structure of Fungi it is important to understand the structure and behaviour of fungi in order to understand how they affect plants. The body of a fungus is made up of fine strands called hyphae. Some hyphae have "walls" dividing them, others will be continuous strands. A tight mat of hyphae is called mycelium. 

Nutrients Uptake by Fungi -

• Fungi absorb nutrients by penetrating the food source with their mycelium
• Individual hyphae of saprophytic fungi secrete enzymes which break down the food source into nutrients it can absorb
• Parasitic fungi obtain nutrients from within living cells producing special sac-like structures called haustoria, which form at the ends of hyphae that have entered living cells. Haustoria absorb nutrients from the cytoplasm. 

How Fungi Infects Plants - 

1. Once dispersed, the spores which land on a host plant will lay dormant until conditions are 

    favourable. 

2. Spores require certain temperature and humidity conditions to germinate.

3. The exact conditions will vary according to the fungi species.

4. On germination, the spores produce a small hypha called a germ tube, which will eventually form the 

    mycelium.

5. Fungi enter the plant tissue via wounds, natural openings, through the cuticle and epidermis.

6. Once inside the plant, the fungi will disrupt normal cell activities by removing nutrients and secreting 

    toxic substances.

How fungi Spread through spores over large distances and depending on the type and it spread by air, water, insects, birds, people tools and seeds.

Signs and symptoms of Fungal Diseases:-

Blights - First shows as large irregular, water soaked areas on soft leaves and stems; can spread to fruit.  Can spread rapidly and quickly ruin a crop.

Cankers & diebacks - Lesions on stem of trees and shrubs. Plant will die out above the canker if it girdles the stem.

Damping-off - Infected seedlings collapse, fall over and die. Pythium and Phytopthora  (wet soils). Rhizoctonia spp. (dry soils)

Downy Mildews - Pale areas on the upper leaf surface, often watery appearance. Corresponding "downy" growth on lower surface. Requires humidity and leaf wetness.

Galls - Abnormal swellings or nodules on a plant. Can occur all plants part depending on the infection.

Leaf spots - spots of various patterns and colours on fruits and leaves. Size, colour margins, signs, habit will all assist identify  fungi.

Moulds and Rots - Plants parts decay. Mycelium shows on moulds but absent with rots. Some moulds will not cause decay - sooty mould contained on plant surface. Root rots cause wilting.

Powdery Mildew - Discoloured and distorted leaves. Upper leaves surface covered in white mycelium. Spores borne on chains on upright hyphae. Require high humidity and temperature but not wet.

Rusts - Postules which raised lumps on underside of leaves are fruiting bodies. Corresponding yellowing on upper side of leaf. May change colour during season as spore type changes.

Wilts fungi e.g Phytopphthora - loss of water from plants. More obvious in herbaceous plants. Woody plants produce short unhealthy shoots, yellowish leaves, wilting and eventually dieback from tips. Collar rot on deciduous trees.

Several fungal symptoms don't fit into previous groups are Turf which has brown patches, fairy rings and red thread. Fruits symptoms  are peach leaf curl, bladder plum, verrucosus and flowers symptoms are tulip fire.

23/05/2013 - Hedge Pruning Unit 21032

My morning class was on Hedge Pruning with Kim Thomas. The class was cancelled due to wet day and I stayed on in Poly Grow Nursery and observed all the plant propagation in the Greenhouse. Then i started to pricking out and potting on the plant named  Corokia x virgata which was cultivated from well branch shrubs with different leaf colours.

 

 

"Corokia x vigrata"  of 20 pieces of small pots

 

Firstly, fill in with many small square pots to the top with potting mix then level  Firmly mix lightly so that the level is just below the top of the pot. Remove the seedlings gently, lift plant by one seed leaf while prising loose the root system from the old small plastic container and replaced it with small pots. Pricking out is the process of transferring seedlings from their first home  to the individual containers. 

 

The term "Potting on" is the name applied to moving a plant into a bigger container. It is a task that needs to be done with some care. The seedlings should lift up to avoid accidental damage. A plant can be replace by damage leaves, but not a damaged stems.   

Finally once the tray is full with small pots which is approximately 20 small pots. Once finished labelled  and water them gently. Then placed them in a sheltered area to grow on. Plants must be well watered as soon as possible after pricking out or potting on. Fungicide may be added to the water.

The weather was cloudy but no rain falls with temperature was 11degree Celsius. Humidity was 80%. 

21/05/2013 on Plant Propagation Unit 20557 - Pricking Out And Potting On

On 21/05/2013 @  Tuesday the class -  Plant Propagation on pricking out and potting on the plant Dianthus confetti. As soon as the seedlings are large enough to handle they should be spaced further apart or put into individual pots to allow for maximum growth.

Always do this as soon as the first seedlings leaves and fully developed and before the next few leaves form. At this stage - root system large enough to survive but not so large and should handle it carefully.

When lifting seedlings by holding the plant by one seed leaf, not by the stems. These stem is easily crushed and the plant may wilt and die.

Firstly, fill in with many small square pots to the top with potting mix then level off with a level board. Firmly mix lightly so that the level is just below the top of the pot.

Secondly, remove the seedlings gently, lift plant by one seed leaf while prising loose the root system with a dibber at the same time. Seedling should come easily with the root system intact.

Thirdly, make a hole with a dibber in the medium, large enough for the root system to be placed in without being bent upwards. Then gently firm the mix around the seedling. Prick out seedlings into row and than evenly spaced apart.

Finally once the tray is full with small pots which is approximately 45 small little pots. Once finished labelled  and water them gently. Then placed them in a sheltered area to grow on. Plants must be well watered as soon as possible after pricking out or potting on. Fungicide may be added to the water.

14/3/2013 - 09/05/2013 - Pests and Diseases Unit No 27208

My class on Pest and Diseases was conducted by Lisa Burton and mainly emphasis on Pest.

Pests and their Parts

Insects - have six legs, three body parts (head, thorax and abdomen) and a pair of antennae (feelers) and the adults are often winged. However, young stages - like caterpillars, grubs and maggots - may not resemble adults. Some insects pests are chompers, biting chunks out of leaves and fruits, often suckers, feeding on plant sap.

Mites - are related to spiders and have eight legs and one body part, without antennae or wings. They have an external skeleton or body skin that they need to shed and replace several times as they grow. All pest mites are very tiny, with the largest being barely 0.8mm long, some are as little as 0.2mm long. Mites feed by scraping and sucking plant sap from leaves.

Nematodes - are also sometimes known as "eelworms". They are very tiny, slender worms, a few of which live inside plants and cause them damage. Typically they are 0.2 - 0.8mm long. Larger nematodes can only just be seen with a hand lens.

Molluscs - are slugs and snails with a soft fleshly body that does not have an external skeleton. Snails have a shell, but slugs don't. Slugs and snails do not have legs but have four tentacles or feelers. Molluscs rap plant leaves, causing ragged holes.

Evidence of the pest or pathogen may be seen in two ways:-

1] Symptoms -
    The damage or growth response a plant makes in response to the presence of a pest or pathogen.

2] Signs -
    Those tell-tale structures of a pest or pathogen that are sometimes (but not always) visible on
     plants.

Various pests may cause problems when propagating, but as they attack a wide range of host plants they need only be considered in a general way so that the gardener can recognise them and treat them appropriately.

When infested propagating material, or a plant, is placed in a propagating environment, the increased levels of temperature and humidity often cause a population explosion. 

It is important, therefore to propagate, whenever possible, from material that appears to be free of pests. it is safer and often easier, to control pests on stock plants before taking cuttings rather than to treat the cutting later before they have established themselves as plants. This is not always possible however, and routine pest control measures should always be taken in the propagating area to combat invasions of pests from infested plants elsewhere in the greenhouse garden.

Aphids @ Sap Sucking Insects

Insects, such as greenfly and blackly, are invariably  present, in small populations on almost all plants during the growing season, and i is important to control them not only because they can debilitate plant material very quickly with rapid population build up but also because they may carry virus diseases.

Some aphids are easy to identify because they are found on just one host plant, or a few closely related plants. Others have a characteristic colours or markings. Some growers are taken by surprise when aphids infestations suddenly appear - often as if by magic. The reason for their surprise is that the tiny aphids that have  been establishing the population for several months have goon unseen. Many such aphids survive during the cooler winter months, hidden without plant buds. it is only at the onset of longer days and warmer spring weather that they multiply rapidly and move out onto lush spring growth - to the dismay of many gardeners.

Occasionally aphids or greenfly are found on cuttings and more rarely on newly germinated seedlings. When they are found on cuttings it is usually because some were already present on the material when the cutting are made.

Typically, aphids may cause : stunned shoots, distorted and curled leaves, wilting, honeydew and sooty mould.

Leaf roller @ Chewing Insects

Are the young larva stages of butterflies and moth and are one of the most common plant pest. Many of the caterpillars attacking plants in New Zealand has come from overseas. Caterpillars can cause damage to plants and to avoid this is essential to detect their presence early.

Mature green looper caterpillars are larger and stouter towards the rear end. Their bright green colour makes them quite hard to detect on plants, particularly when they are small and tucked under leaves.

Green looper - usually 35 - 40 mm long are stouter towards the rear end. Their bright green colour make them quite hard to detect on plants, particularly when they are small and tucked under leaves out of sight. They feed on a wide range of herbaceous plants and several weeds.

Leaf roller  caterpillars rolls and tie up leaves to make a shelter. They damaged plants by feeding on leaves and in orchards they also feed on the out side of fruits by damaging the surface. The larvae of each species are not easily distinguished and are one most serious and common horticultural pests.

Thrips @ Rasping Insects

Usually are tiny 2 -3 mm long insects. Adults are usually black and the nymphs cream. They infest and damage the the foliage and flowers of many ornamental plants, vegetables and fruit crops. Thrips may also infest bulbs and corms in storage.

The presence of brown / black sticky spots of excrement on the underside of leaves is a characteristics feature. The rasping-sucking mouthparts cause flecks and a silvery appearance to the surface of flowers, leaves and fruits.

White butterfly @ Chewing Insects

The most notorious and common pest attacks brassica vegetables (such as cabbage and cauliflowers). The dull green caterpillars grow to 30mm in length. They eat holes in leaves and plants may reduced to a collection of leaf skeletons. The white butterfly adults flit over the leaves on warm days from early summer to autumn.

Codling Moth @ Chewing Insects

Apples are damaged when the young codling moth caterpillars burrow through the skin and into the fruits. The larvae family reach the core where they consume the seed and much of the core itself. Mature larvae leave fruit and move down the tree in search of suitable protected spot beneath loose bark flakes, or in brk crevices, where they build a cocoon, become dormant. Pears, stone fruits and walnuts may also be attacked.

Gras Grub Beetles @ Chewing Insects

It is also called brown beetle. mature grass grub beetle are creamy white and 10-20mm long. They feed on the plant roots in the soil and curl up if you disturb them. Pasture, turf, container plants and field grown plants in nursery lines are frequently attacked. They feed on the foliage and may occasionally  strip the leaves of cherry and plum trees but they feed on the leaves of many other plants.

Whitefly  @ Sap sucking Insects

They are several whitefly pests, and greenhouse whitefly is the common and damaging. All whitefly are tiny insects that have scale-like young stages, commonly referred to as nymph through more accurately they are larvae, a pupal resting stage, Whitefly can be difficult to distinguish, particularly where different species share a preference for the same host plant.

Scale @ Sap sucking Insects

Most are tiny insects 2 - 3mm long that have hard coverings and they are often dome and mussel shaped. Scales are commonly brown, black, grey or white. Scale insects fix themselves to leaves and stems and suck sap. Infested leaves turn yellow and often are covered with copious quantities of sooty mould. Some scales live beneath bark and so are not easily seen.

Apparently at teh end of this session whe gave a test and Assesment to meet the competency of the topic.