Diseases And Pests
Seedling diseases, effective in cotton during germination and boom periods and referred as dissolving in regions where cotton is grown are caused one or more of Rhizoctonia solani, Fusarium spp., Pythium spp. fungi.
These fungi spending the winter in the soil harms the cotton seeds germinating after the sowing and cause the seedlings to die before or after booming.
The most effective methods for fighting against this disease which is seen frequently nearly in all regions where cotton is grown;Crop alternation
- It must be planted when soil temperature is 18 °C on 8-9 cm deep.
- Deep plantation should be done.
- Very early plantation should be avoided.
- It must be planted on a ridge.
- Alternation should be used especially with grains.
- Seed should be disinfected with an appropriate fungicide (Delinte seeds are disinfected against such factors, it does not require additional fungicide disinfection).
In Verticillium disease seen generally at the end of the season, discoloration symptoms start with lower leaves and expand through above and cause whole plant to dry. When stem is cut transverse, vasculars can be seen as brown dots.Most important struggle methods against Verticillum discoloration:
- Crop alternation
- Using resistant hybrids
- Removing harvest waste
- Appropriate fertilization and irrigation (over-irrigations increases disease).
Larva and mature insects developed from eggs left on lower surfaces of the fresh leaves, nurture by suction. It can reproduce 9-10 times a year, it reproduce so fast especially during the boll period of cotton. It develops well under humidity.
- Due to sweetish material excreted during nurture, nigrescence contaminates the plant and lowers the quality; this causes problems in ginning,
- Larva sucking plant juice led plant to weaken and stop the growth,
- It causes early aging and death of the plant.
It is important to disinfect on time. It is suggested to start disinfection when there is 5 mature of 10 larva-pupa found per leaf, however, one should be more sensitive considering the increase of the pest and condition of the plant.COTTON APHID:
It is also called Psören, Ballık, Zenk; it has winged and non-winged forms. Pest especially increase under cool (cloudy) and humid atmosphere.Harms:
- Yield lowers in the plants that are harmed as well as quality.
- It sucks early suckers and leaves of cotton, leading leaves to curl and discolor and stop the plant.
- Excreted jammy material covers the plant and nigrescence causes the quality to fall.
- Aphid which can reproduce very fast leads important yield loss if not fought.
When seedling period, if it contaminated 50% or if there are 25 aphid detected per leaf, disinfection should start.RED SPIDER:
It develops on the lower surface of cotton leaves and causes 40% yield loss.
- Yellowing, reddening, drying and falling of the leaves,
- Delay in scalloping
- Fall of flowers and scallops
- Diminution of bolls
- Dry and hot atmosphere is suitable for red spider
- It can reproduce 10-20 times a year.
Pest especially starts to give harm from the edges of farm. Therefore, before planting or just after, farm edges should be disinfected. Covering disinfection should start when seeing 5 mature pest per leaf.COTTON LEAF FLEA:
- It is a pest seen in all cotton regions and given significant harm and led to yield loss.
- It causes leaves to curl and redden.
- It gives harm not only by sucking the juice of the plant, but also by releasing poisonous material inside the plant.
- Despite it is seen through all cotton season, it increases especially after first irrigation.
When coming across intense flights of leaf fleas during farm controls, disinfection should be carried out.GREENWORM
- Butterflies of the pest which spends the winter in soil as a pupa start to be seen in Çukurova in April, in Aegean in May. Generally, they are active at nights.
- It lays its eggs especially on the above parts of cotton, fresh, sucker, scallop, flower and bolls.
- Larva cracking eggs generally harm the plant from above to below to scallop, flower and bolls.
- It gives harm to first scallops which comprise the most of the yield as first generation and these scallops fall. Larva which harm flowers decrease boll generation. Bolls harmed do not bloom and fall.
Disinfection is carried out when there are 2 small larva in cotton line of three meters during controls on the field. For a successful control, precautions should be taken early.COTTON PRODENIA:
- Butterflies hiding in dry and dim places during the day, lay eggs at night.
- They lay eggs as 200-300 packs on the lower part of young leaves.
- Larva first eat the lower tissue of leaves and make them a thin layer, as they grow, their harm increase, leaves are full of holes.
- They eat scallops and flowers and break into the boll to eat.
- It can reproduce 4-5 times a year.
It should be disinfected when 5 larva in 10 plants or 2 eggs in 25 plants are seen.THRIPS :
- It causes significant harm especially during seedling period of cotton.
- In our country, thrips which causes serious harm especially in Southeastern Anatolia region, causes slow growth of the plant by sucking the juice of leaves, flower and other parts of cotton.
- Sucked leaves lead to silver stains. If contamination is high, leaves are curled, become brown and fall.
Starting from cotton seedling period, farm should be under control until first hoe, if 15% of the seedlings are contaminated, they should be disinfected.PINKWORM :
- Especially in recent years, it leads serious damage in cotton plantations. It is nurtured with generative organs like flower, scallop and boll. It prevents scallop and flower development and fruits.
- In boll, they enter bolls and cut the fibers and eat cottonseed, a boll with a pest inside is called blind boll and does not bloom.
- It is more apparent damage pinkworm gives to flowers. Flower with a pest inside does not bloom and become the shape of a badge.
Insecticide usage against pinkworm is not effectual since pest is always fed inside. Most effective control methods against this pest is cultural precautions;
- Using certified DELINTE seeds
- Removing and wiping off harvest waste after cotton harvest.
- Vegetation period should be used for cultivars that are short, early harvested.
Matures are yellowish red or pale yellow. It has wings with wavy gray. Its nymphs are red and turn to green and pinkish. Matures are 3-7 mm at length.
It spends the summer as mature or nymph under stones, dried plant remainders or tree peels. In spring, they activate and become pests on the fresh tips of plant suckers. Later, they pass to cotton and other hosts to lay eggs. Little yellow nymph cracking eggs cause new contaminations. After 2-3 weeks, they molt 5 times and become mature.Control :
Excessive nitrogen and irrigation should be avoided, plants (over line) should not be too frequent. After the harvest, cotton tips should be gathered and burned.
Disinfection should be done in a windless and rainless weather, early in the morning or in the evening. All parts of the plants should be disinfected.
Control should start when 5 pests detected average per plant in early period of 100 examined plant diagonally. Strong insecticides like Azinphos or Carbaryl or other ones suggested should be used.
Soybean is affected to an important extent by weeds during its early stages of development. Therefore, in order to get a good yield, weed control should be conducted.Some weeds seen in soybean;
- Mole plant
According to development stage of the plant, after the first or second irrigation, interim hoe should be done and plant stress due to soil compaction should be prevented.
During hoe, it is important not to perform middlebreaking. Because this leads to decrease in first broad bean height and losses in harvest.
Herbicide can be used after EARLY boom for chemical control.
|Mole plant||125 ml/da|
Pests: Green worm, Red spider, White fly, Cotton prodenia, Striped cotton prodenia, Smelly green insect give harm to soybean.
- For green worm: Active matter thiodicarb-(80%)-dosage 90 g/da
- Smelly green insect: Active matter cyphermethrin-(200g/l)-dosage 70ml/da
- White fly: Active matter Pyridaphenthion-(400g/l)-dosage 300 ml/da
- Red spider: Active matter fenbutatin oxide (550 sc)-dosage 135 ml/da
- Bud rot
- Soybean mosaic virus
- Coal rot
In control of these diseases, rather than disinfection, using healthy seeds and extermination of plants with virus is preferred.
Against coal rot, precautions should be taken to prevent soil compaction, after deep ploughing and irrigation… interim hoe should be performed to ventilate the soil.
It causes up to 100% yield decrease and/or decomposition at the farm.
- In early stage, especially cool/cold rainy weathers and flooding soils, it kills completely if it contaminates the plant during germination or seedling.
- First symptoms are yellowing in cotyledon leaves and later, all plant.
- Cool air and humidity, wet plant & leaves increase infection, spores of white ash color occur under the leaves
- Decrease in head diameter and grain, curling in two leaves, shortening
- In late contaminations, yellow dots in leaves become dead zones and scars, later.
- Scars in root, discoloration, branning and decrease in development of capillary root.
- The most effective control is using resistant hybrid.
- Crop alternation - at least once in 4 years, sunflower should be planted to the farm.
- Prevalent in dry and hot regions.
- It is seen in more than 300 plants in the world, Macrophomina causes 64% yield loss in sunflower.
- Decrease in grain yield is caused by decrease in one thousand grain and head diameter. Disease decreases oil content in grains, and affects negatively oil acid composition and color.
- It appears during the grain filling stage.
- First symptoms are yellowing and pale appearance in lower leaves, dead zones on stem from ash color to silver grey.
- These zones become 30-40 cm in width through the top and turn into brown and black.
- Beneath the outer layer of stem, there could be very small sclerots, plant juice dries and become grey-black.
- Diseased plants reach maturity early, generates weak tip and head and thin grains, these leads to yield loss and due to these, in wind, tips may be broken.
- Roots also become brown and inside it seems grey due to sclerot formation.
- Resistance is obtained and commercial hybrids resistant to it are developed.
- Those varieties tolerant to drought are also seem to be resistant to the disease.
- However, these hybrids, despite they have stay green feature and resistance to Phomopsis, there is no significant relation between stay green feature and resistance to Macrophomina.
- Excessive nitrogen use fastens development of disease, irrigation during blossoming and grain filling prevents it.
- Benomyl based seed disinfections may be effective in controlling the disease.
- Scleretonia sclerotiorum is one of the most prevalent diseases in plants with more than 374 cultivars.
- It gets transmitted from the root to sunflower.
- It may cause up to 70% yield loss under aqueous and moist conditions, high temperature (20-30oC) and humidity incites the disease.
- In sunflower where three different types of it can be seen, S. Sclerotiorum has wide and shapeless and bigger (1-5 cm in diameter) sclerots.
- S. minor has small, uniform, circular 0.5-2 mm diameter black sclerots.
- S. Sclerotiorum has wide and shapeless and bigger (1-5 cm in diameter) sclerots.
- Scleretonia rolfsii has small and circular sclerots as S. minor changing from brown to black, but it has connections also shaped as gripper.
- Paleness and root rot in scleretonia minor
- All symptoms in scleretonia sclerotiorum.
S. rolfsii causes collar rot and is seen mostly in tropical or subtropical areas and Mediterranean countries, therefor it does not cause yield loss.
Symptoms - Stem, leaves and root
- Scleretonia paleness and root rot, with micelle generated from germination of sclerots infects the plant from germination to physiological maturity.
- However, it is mostly seen just before germination and when root reaches maximum maturity.
- At this stage, roots rot due to disease and are not able to absorb water from soil, paleness symptoms start.
- 4-7 days after first paleness symptoms, plant completely withers and takes a pinkish color.
- Infected plants are in the same line or in a certain region.
- Pale plants have grayish green to brown color and their roots have cankers also called white mold, whitening occurs from the base to 10-20 cm of the plant in moist environments.
- Plants can easily become flat with harsh wind due to root rot.
- There are sclerots of 3-6 mm diameter inside and outside the stem.
- There are brown stains in root and stem if plant is infected during the light or late period of the disease.
- However this causes paleness and stems get weaken and sensitive to become flat.
Symptoms - Head
- It appears before or after blooming.
- Especially the rain fall from blooming to harvest fastens infection and development of the disease
- Despite the first symptoms' appearance on the back of the head, spores infects sunflower through old flower organs.
- It starts with juicy rotten dots and whitish regions on the back and succulent sides of the head.
- Later, disease gets inside the head and covers all head and grains with micelle similar to a white web.
- In advanced stages only the main frame of the head remains and it seems as a broom from far.
- All infected grains fall from the head and some sclerots as big as grains may be harvested with healthy plant grains.
- Despite benomyl and mixes and some herbicides as a cover disinfection may increase root rot and scleretonia paleness, they don't offer an effective protection, there is no certified medication in the world.
- In addition, seed disinfection is another way of control. Benlate, thiophanate methyl and Iprodione effective fungicide prevent germination of scleretonia spores in the soil.
- In scleretonia collar rot, chemical control is not that much successful.
- Calcium nitrate or sulfate fertilization is suggested since it increase durableness in the stem and therefore, decrease the effects of the disease.
- Crop alternation is not much effective since it can stay in the soil for 7 years and scatter its spores to 1 km.
- In genetic control, only middle level robustness can be obtained and it could not be transferred to commercial hybrids.
- In cleretonia head rot, a fungicide mix of vinclozolin and carbendazim got a certificate from France, however, for effective control, disinfection should be done through head and there are certain problems especially with the inclined head varieties.
- It is a significant problem especially in France and other central European countries, it does not have any economical harm in Turkey.
- It has two morphological and biological kinds, Alpha and Beta conidia.
- Rain, humidity and increase in temperature provide a suitable environment for disease development, from head formation to blooming.
- It is seen after blooming and early sowing increases infection risk and degree.
- First, small dead dots with yellowing around all along the leaf trachea, on the edges of leaves.
- Leaves wither and die shortly after and infection passes to stem.
- The most important symptom of the infection is canker or dead regions with light brown scars on the middle and lower parts of the plant stem.
- These regions cover all parts where leafstalk connects stem and around the plant stem.
- Later, they turn to grey-brown, when plant matures it turns to grey.
- At the last stage of the disease, plant completely withers.
- In light infection, early maturity is seen and oil content decreases.
- Comparing with phoma, scars are wider and longer (15-20 cm), in lighter color and typically caved in.
- Phomopsis causes decrease in pith and sap and plant becomes weak.
- Comparing to scleretonia, Phomopsis has darker brown micelle and sclerots.
There must be a microscopic examination when symptoms mix.Botrythis Cinerea Pers.
- It can always infect sunflower during maturing period. It can attack from any part of pathogen plant tissue.
- Some infected seeds may lose vitality. After boom, stalk, leafstalk, leaves and maturing head may be attacked.
- Cuticula mechanically enter cell walls enzymatically. Infection generally is transmitted from scars.
- It is seen more in cool and moist environment.
- It leads yield loss up to 36%.
- If decrease in oil content, decomposition in oil acid composition and quality appears near harvest, it gives only superficial harm, does not affect yield.
- However, like others, infected grains that did not decompose, can explode in high temperatures or in fire.
- Symptoms start with brown caved in dots on the back of the heads, later, in moist conditions, different than other head rots, become covered with gray micelle.
- Another difference is that due to superficial development of the disease, there are no black spores inside the head. Through the end of the disease, it passes through the front of the head and covers the grains before and after maturity.
- It has no chemical and cultural control, resistant hybrid development continues.
- This disease cause head tissue to turn brown, soft and jellyish. In rainy weathers, thick and dangerous fibers of fungi may be apparent over infected tissue. Infected seeds have lower germination and higher death ratio. Head may fall apart. After blooming infection nurtures from the harms given by hot rainy weather, birds, hails, and moth.
- At the end of blooming, dichloran and cooper applied to head may decrease the infection.
It is not so much an important fungal leaf stain disease. Disease appears as small circular stains on the leaf, around it there are light color stains. The tissues where this stains appear lose vitality. Fungal spores may be found in mature leaves. In rainy weathers, and moist environments it can spread better. As a precaution, stubble or using resistant varieties may be performed. It is first seen at the lower leaves of the plant. Later, it spreads through above. It is seen in high temperatures and after blooming.Alterneria Leaf Stain
- Alterneria species causes seedlings to rot and collapse. Dry scars and velvet mold points appear on the green parts of the plant (stalk, leaf, head). Flower and its parts may be attacked.
- When fungus enters the seed, infects it and this leads a decrease in yield and in quality. Generally, alternia is seen in plants which before were harmed by another factor.
This disease is seen as brown black scars above the soil parts of the plant, especially at the tip of leafstalks. In this regions, inside the stalk becomes brown and due to drying effect of the fungus it makes tissue brittle and sunflower may collapse. The most suitable degree for this fungus is 25. It has no economic significance in Turkey.Puccinia Helianthi
It can attack all above the soil parts of the plant. Due to weather conditions, it starts generally with blooming. This fungus develops well in hot temperatures and can become an epidemic and give an important harm. For a small attack, there is no need for fungicide. Its economical significance is minimum.Orobanche Spp
Mycelium of orobanche parasite is specialized in order to obtain water and plant food and its leaves become smaller. It has stalks without branches carrying different colored flowers. Its fruit is in shape of capsule, it has very small black-brown seeds (0.4 mm). One orobanche has nearly 200,000-300,000 seeds. These small and light seeds can spread with cultivation tools, water and wind. They can preserve themselves for 15-20 years in soil. Orobanche is stimulated with the releases from roots of sunflower and gets germinated and forms a mycelium to get a grip on the host plant. Parasite, thanks to this organ, holds on to roots and gets inside the root. Orobanche parasite, then, reaches to vasculars and nurtures there to become orobanche plant. This parasite gives harm to the plant until it is seen above the soil. Orobanche which threatens sunflower is called tuberculosis weed or monster weed in colloquial language. Orobanche causes a decrease in oil and protein content, plant height, one thousand grain weight, head diameter and yield per plant. Mycelium of orobanche parasite is specialized in order to obtain water and plant food and its leaves become smaller. It has stalks without branches carrying different colored flowers. Its fruit is in shape of capsule, it has very small black-brown seeds (0.4 mm). One orobanche has nearly 200,000-300,000 seeds. These small and light seeds can spread with cultivation tools, water and wind. They can preserve themselves for 15-20 years in soil.
Chemical control is possible against orobanche and also, resistant hybrids can be used to avoid this parasite.
"O" and "T" races of this pathogen which are also known as southern corn leaf burn are prevalent. "O" race generates small stains of red to brown with black lines around, between the strings in warm, moist environments. "O" race is a leaf pathogen and is not seen generally in stalk tissue and grains; however, in some stem glume. This race does not have much significance despite being prevalent.
"T" race of the disease are pathogenic especially in Texas cytoplasm corn varieties and gives harm more in these varieties. The lesions of this race are wider, in a similar color and covered by shiny yellow lines. "T" race is seen in stems, stem stalks, stem glume and leafstalks above the soil.b)- Turcicum Leaf Burn = (Hleminthosporium turcicum = Exserokilum turcicum)
Northern leaf burn disease gives harm right after stem and tip crest blooms. First symptoms are small stains, seems wet, in a slightly oval shape on the leaf. These stains, later, develop and become long dead regions. Firstly, they are seen on the lower leaves and as the plant grows, their number and region enlarge and they cause all leaves to burn at the end. In severe cases, as the plant develops, all green parts of the plant burn. Plants seems to have a pale gray color and this color resembles to a plant harmed by cold.
Examples of medications used;
Opera Max, Rotanett
These diseases appear in early periods are seen in low drainage and inadequate oxygen soils. Late period root rots increase with Fusarium species, maturity period, ageing of root tissues and farm compaction. These late period rots are the start of the stem rot.
Symptoms of Disease, Economic Significance and Prevalence: When infected seed is sown or healthy seed is infected in soil, germinating or germinated seedlings can be infected above or below soil; germination is prevented or seedling burn may arise, curving in and gives harm. At the beginning, at the farm, there are irregular lines and pale seedlings.
Harms given to corn during its fast development period by Fusarium and Pythium species appear as root collar and stalk rot. Root collar rot appear at the soil level. Before, plants require lots of water in short term. Pythium causes spin and bend in stem axe in plants. Plant collapses and at the parts where it touches soil, supportive roots appear.
Pythium collapses in a brown, juicy, soft and fast manner at the first joint near the soil surface in which corn is infected root collar and stalk rot. Stalk rot can be seen between fresh joints, before or after top crest appears. Fusarium stalk rot is seen in joints, stems and tips of stems.
These losses causing corn root, root collar and stalk rots incited by soil fungus pathogens are affected by environmental factors. Increasing nitrogen dosage, after 12 kg/da cause the disease to increase; it is high stem rot in the frequency of 9000 plants/da and yield is also decreasing. Stubble burning has no positive effect on root and stem rot caused by Fusarium.
Examples of medications used:
As seed medication, Vitavax, Maxim.
Disease is transmitted with infected soil and plant wastes. Spores are very resistant to winter conditions. Klamidospores are especially able to stay alive for 8 years in sand and hot soils. They stay alive in the stomachs of animals which eat infected plant wastes. They can be transferred to the farm again with fertilization and be a source of infection. Infection can be transferred through mechanical ways such as wind to the plant; spores can enter to grass streaks, membrane of epidermis cells, stomats and from scars and bruises caused by humans, animals and insects. Rain is an important factor for disease to develop. In the years when it rains at the end of the summer, disease is seen more frequently. Irrigation in drought incites the disease also.
Above the soil parts of the plant, in leaves, stems, fringes and male flowers, it can be seen.Foremost precautions taken for minimalizing or preventing the harm:
- a - At least 3-4 years of crop alternation must be performed where corn smut is harmful.
- b - Too late and too early sowings must be avoided.
- c - Smut pouches should be removed before maturity.
- d - Infected plant wastes should be burned or buried so deep. It should not be given to animals.
- e - Injuring plants and giving nitrogen fertilization should be avoided.
- f - Plant injuries should be prevented by controlling insects.
- g - Resistant hybrids should be suggested.
Chemical Control: Infection source of the disease is the infected soil; so, in order not to infect clean soil, seeds should be disinfected.
Examples of used medication:
As a seed medication, Vitavax, Maxim
Three important leaf blotches are seen in corn. These are Regular Blotch, Polysora Blotch and Tropical Blotch. These become apparent just before the top fringe appears.
Regular Botch (P. sorghi) generates small brown dusty fringes at both sides of the leaves. Later, epidermis tears and fringes become black when plant matures.
Fringes originated by Polysora spp are lighter in color and more circular than those of regular botch. As plant matures, they become darker. In this botch, fringes appear at the both side of the leaf. Tearing of the epidermis occurs later than that of regular botch.
Fringes of tropical botch are under epidermis, small and changing shapes between circular and oval. In the middle of fringe, it can be yellow to white. There is also a hole. Fringe sometimes get darker however the middle part stays light.2-CORN PESTS
a)- Corn wire worms They eat germinating seeds of the plants. It is controlled by seed disinfection.
Examples of medication used; Poncho, Cruiser, Gaucho, Cosmosb)- Corn grey worm
They cut the root collar and eat the roots of the plants; they cause the plant to break down and dry. Chemical control: worms come up to surface after sunset, they are controlled by poisonous bait and contact medication on the surface.
Examples of medication active matters: Lambda-Cyhalothrin, Deltamethrin, CypermethrinC)- Corn stem worm
They eat grains in stem and cause yield loss. They increase the bacteria activity with waste production and cause the stem to rot. 3 races of them can be seen in June, July and August in Mediterranean region. Two races can be seen in July, August in Aegean region. In other regions, generally, only one race can be seen. Example of medication used;
Larvin, Fastac, Dursban 4d)- Corn Stalk Worm
Corn stalk worm in leaf streak and stem opens tunnels, these tunnels cause corn to be infected by stem infections, it leads stem to narrow and lose elasticity. Therefore, breaks in stem may occur. This increases harvest losses.
In control of both pests;
1- Corn stems should not be eaten by animals after harvest and left over stems should be shivered and soil must be toppled.
2 - If there is a possibility of infection, drill should be performed with systemic medications when plant is 20-30 cm.
Examples of medication used;
In addition to systemic medications, contact medications: Cypermethrin, Zetacypermethrin
When corn has 2-3 leaves, they eat leaves and cut growth cones and leads important damage.
Nurelle, Gushation, Metnion
YThis pest lies on leaf and top fringe, it sucks the juice of the leaf. General symptoms are withering and discoloration. Leaf turns to yellow and red, if population is dense and temperature is high, it leads to death.
Active matters and medications:
Carbosulfan, Alphacypermethrin, Lambda-Cyhalothrin, Furathiocarb
|Leaf Symptoms||Stem Symptoms||Root Symptoms|
|Normal healthy plant||Dark green||Stem durability and appearance of gradation region is good||Extensive and big roots are hard to remove from soil.|
|Nitrogen||Yellowing lower leaves and curving of the middle streak|
|Phosphate||Reddening in young leaves||Underdevelopment, curving, weak gradation||Shallow and under spread roots.|
|Potassium||Reddening leaf tips and edges||Dark brown discoloration in joints|
|Magnesium||White or yellow lines parallel to leaf streaks|
|Calcium||Tears in leaf tips||Discoloration in root, supportive root generation in 3th and 4th joints. Acidic soil or lacking calcium|
|Drought||Light green color of leaf edges curling through the streaks||Low gradation and elasticity in stem|
|Herbicide Damage||Late maturity in leaves||Twisted stem||Bent roots or unified support roots.|
|Miscellaneous||Little yellow or brown oval dots (leaf diseases)||Fractured stem (corn worm damage)||Root streaks are flat and underdevelopment in plant (hoe deficiency)|