Academic literature on the topic 'Corn root rot. Corn Plants, Effect of patassium on. Plants'

Sweet corn (Zea mays L.) varieties carrying the sh2 gene are in high demand, but such varieties have poor stress tolerance, especially during plant establishment. Trichoderma harzianum Rifai strain 1295-22 is a biocontrol fungus developed to provide season-long colonization of crop roots. It has the potential to reduce root rot and increase root growth. In the absence of detectable disease, colonization by Trichoderma increased root and shoot growth by an average of 66%. The enhancement was not uniform among the plants. Low- and intermediate-vigor plants were larger in the presence of Trichoderma, but high-vigor plants were not further enhanced by the fungus. Seeds that were subjected to oxidative stress with 0.05% NaOCI had much-reduced vigor; subsequent treatment with Trichoderma fully restored vigor. This result indicates that the damage caused by hypochlorite is specifically repaired by Trichoderma. Treatment of imbibed but unemerged seeds with cold (5/10 °C night/day) for varying periods reduced subsequent growth. Plants with Trichoderma-colonized roots were 70% larger at all durations of cold treatment. The absence of interation indicates the growth reduction due to cold and the growth enhancement due to Trichoderma are by different mechanisms. Allelopathic reduction in root growth by rye was mimicked by applying benzoxazolinone to the soil. Trichoderma-colonized roots grew faster, but the characteristic shortening of the radicle still occurred. There was no interaction between Trichoderma and allelopathy, indicating that these two treatments affect growth by independent mechanisms. The different ways that growth was enhanced by Trichoderma lead us to propose that this fungus acts, in part, by reversing injurious oxidation of lipids and membrane proteins. Root growth is markedly enhanced by colonization with Trichoderma harzianum. This enhancement can restore some stress-induced growth reduction and may directly reverse oxidative injury.

У результаті польових досліджень було встановлено вплив попередників, системи удобрення і способів основного обробітку ґрунту на ураження рослин пшениці озимої кореневими гнилями в короткоротаційних сівозмінах зони недостатнього зволоження. Найбільше уражених рослин пшениці озимої кореневими гнилями виявилось в зернопросапній сівозміні, де попередником була сама пшениця, а також в зернопаропросапній сівозміні, де попередником був чорний пар. Найменше уражених кореневими гнилями рослин пшениці озимої (15,3–20,0 %) за найнижчої інтенсивності розвитку хвороби (5,8–7,3 %) спостерігали після кукурудзи на силос. Проведення поверхневого обробітку ґрунту на глибину 10–12 см під зернові культури, в тім числі й під пшеницю озиму, на фоні 6,25 т гною + N33,8Р45,0К33,8 + солома + гичка в просапній сівозміні після кукурудзи на силос спричинило найбільше ураження рослин пшениці кореневими гнилями (24,4 %) з підвищенням інтенсивності розвитку хвороби до величини 10,5 %. Проведення оранки під усі культури в просапній сівозміні за внесення за ротацію сівозміни з розрахунку на 1 га ріллі 6,25 т гною + N33,8Р45,0К33,8 + солома + гичка забезпечило найвищу урожайність зерна пшениці озимої – 4,39 т/га. As a result of field studies, the effect of predecessors, fertilizer systems and methods of basic tillage on the damage of winter wheat plants by root rot in short-rotation crop rotations in the zone of inadequate moisture was established. The most affected wheat plants of winter rot was found in grain sown crop rotation, where the forerunner was the wheat itself, as well as in the grain-para-breeding crop rotation, where the black pairs were the precursor. The least affected by root rot of winter wheat plants (15.3–20.0 %) at the lowest intensity of disease (5.8–7.3 %) was observed after corn silage. Conducting surface cultivation of soil at a depth of 10–12 cm under grain crops, including under winter wheat, against the background of 6.25 t of manure + N33.8R45.0K33.8 + straw + gill in the crop rotation after corn on silage caused most defeat of wheat plants by root rot (24.4 %) with an increase in the intensity of the disease to a value of 10.5 %. Providing plowing for all crops in the fertile crop rotation for rotation of crop rotation per hectare of arable land of 6.25 tons of manure + N33.8R45.0K33.8 + straw + lace ensured the highest yield of wheat of winter wheat – 4.39 tons/ha.

Goal. To investigate the antagonistic activity of a new strain of Trichoderma viride F-100076and its effect on the formation of micromycetes populations in the root zone of corn plants underfield conditions. Methods. The antagonistic activity of T. viride F-100076 was studied by the method of mixed (counter) cultures on wort agar using phytopathogenic fungi, which were isolated andidentified in the Laboratory of Plant-Microbial Interactions. The appearance and type of relationship were registered using a scale modified by Symonian and Mamikonian. The number of micromycetes was determined by the method of soil dilutions. Isolation, accounting and cultivation of fungiwas carried out according to conventional methods. Micromycetes were identified according to thedeterminants appropriate for a specific systematic group of micromycetes. Results. It was foundthat T. viride IMB F-100076 is characterized by high antagonistic activity against a wide range ofphytopathogenic fungi, showing hyperparasitism as early as on the eighth day. The highest antagonistic activity of the strain was found against: Alternaria radicina, Acremonium strictum, Acremonium сucurbitacearum, Fusarium oxysporum var. orthoceras, Fusarium moniliforme var. lactis, Torula expansa (5 points on the corresponding Symonian and Mamikonian scale). Data from the mycological analysis of the sod-podzolic soil of the corn rhizosphere showed that the mycocenosis ofthe sod-podzolic soil of the corn rhizosphere was formed by micromycetes belonging to the generaAcremonium Link, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which the most represented were micromycetes of the genus Penicillium (59 %). The total number of fungi in the control variant was291.00 ± 79.67 thousand CFU/g of soil. The introduction of straw affected both the total number ofmicromycetes and the genus composition of fungi. The total number of fungi in the variant withstraw increased 2.6 times and amounted to 744.00 ± 114.67 thousand CFU/g of soil. The number ofrepresentatives of all studied genera of micromycetes also increased. In addition, the introductionof straw provoked the development of fungi of Bipolaris and Fusarium genera, which can be considered a negative outcome since representatives of these species are commonly recognised as pathogens of root diseases. Application of the fungus antagonist T. viride IMB F-100076 to the soilalong with straw did not significantly affect the total number of micromycetes. At the same time, a displacement of fungi of the genus Bipolaris and Fusarium from the rhizosphere of corn was registered.The number of fusaria decreased from 96.00 ± 5.44 to 23.00 ± 2.32 thousand CFU/g of soil or almost4 times and reached the level of the control variant. Fungi of the genus Bipolaris in the variant withthe introduction of trichoderma were not detected. Conclusion. The antagonist fungus T. virideF-100076, introduced into the soil along with straw, strikes root in the soil and exhibits antagonisticactivity against micromycetes of the genera Bipolaris and Fusarium, which are commonly represented by root rot pathogens of many crops. Thus, the new strain T. viride F-100076 allows increasing theantagonistic potential of the rhizosphere soil of corn and protecting plants from pathogens.

Yield loss of corn following a winter rye cover crop (CC) has been associated with increases seedling disease caused by Pythium spp. We hypothesized that physical separation between the CC and corn could reduce the risk of seedling disease, and benefit corn growth and development. In a growth chamber experiment, corn seedlings were planted at 0 cm and 8-10 cm, from terminated winter rye plants. Root rot severity was assessed at crop development stage V2, and quantitative PCR was used to estimate the abundance of Pythium clade B and clade F members present in corn roots. Radicle and seminal root rot severity was numerically greater when seedlings were planted 0 cm from terminated rye plants compared to seedlings planted 8-10 cm away. Moreover, a greater abundance of Pythium clade B was detected in corn grown within the terminated winter rye compared to corn planted further away (P = 0.0003). No effect of distance between corn and winter rye was detected for Pythium clade F. These data contribute to our understanding of the effect of a winter rye cover crop on corn and will inform field trial management practices for farmers to reduce occasional yield loss of corn following a winter rye cover crop.

Terminating winter cereal rye (Secale cereale L.) cover crops (CCs) 10 or more days before planting corn is recommended to minimize seedling disease and potential yield loss. In Iowa, cold temperatures and frequent precipitation can prevent farmers from following that recommendation and sometimes forcing them to plant corn while the rye plants are still green, referred to as planting green (PG). A field trial was established to evaluate the effect of rye termination shortly before or after corn planting on growth, seedling root disease, and yield of corn. A rye CC was terminated 17 and 3 days before planting (DBP), and 6 and 12 days after planting (DAP) corn; corn planted following no rye was included as a control. Rye biomass, C:N ratio, and N accumulation increased when terminated 6 or 12 DAP corn compared with rye terminated 17 or 3 DBP corn. Corn seedlings were taller from the PG treatments. More radicle root rot was observed when rye was terminated 3 DBP, 6 DAP, and 12 DAP corn than for the 17 DBP treatment and the no-rye control. Generally, greater Pythium Clade B populations were detected on radicles and seminal roots of corn from the PG treatments. Corn populations, ears, or barren plants were not affected by the treatments. In both years, the no-rye control had the greatest corn yield and the 12 DAP treatment had the lowest yield. Our results suggest that PG increased corn seedling root disease and contributed to reduced corn yield.