Journal Of Crop Protection
Volume:11 Issue: 4, Dec 2022

This experiment was performed to determine the appropriate dose of Cyhalofop-butyl (CB) for controlling grass weeds in transplanted rice. CB at four doses, including 50, 100, 150, and 200 g ai/ha was investigated and compared with current herbicides in rice at recommended doses. The results showed that CB 100, 150, and 200 g ai/ha significantly reduced the density and dry matter of Echinochloa crusgalli (L.) P. Beauv. and Paspalum distichum L. over the weedy check; the minimum control efficacy of CB at these doses was 73.3 and 88.3% for E. crusgalli density and dry matter reduction, respectively, and for P. distichum, it was 80% for density and dry matter reduction. Applying CB at all doses (50- 200 g/ha) showed no crop injury symptoms on rice plants. The highest grain yield was obtained by hand weeding, CB 150 g ai/ha, and Tiobencarb treatments, with 5180, 5106, and 5051 Kg/ha, respectively. CB 200 g ai/ha was on par with CB 150 g ai/ha, and there was no significant variation between CB 100 and 200 g ai/ha in rice grain production. Finally, it was found that the application of CB 100 g ai/ha is an efficient grass weed control practice for improving the rice yield.

Apple decline, responsible for seedlings root and collar rot in nurseries, is an important disease. Some Oomycetes species were associated with this disease. This study aimed to control this severe decline disease. The effect of six chemical products against Pythium ultimum and Phytopythium mercuriale associated with apple seedling decline was evaluated using in vitro poisoned food technique and in vivo greenhouse assays. The carbendazim was effective at 10 ppm against P. mercuriale (89.3%), while at 100 and 250 ppm the values were 70.06% and 75.30% for P. ultimum, respectively. The dose 2000 ppm of mancozeb completely inhibited the mycelial growth of P. mercuriale and P. ultimum. However, fosetyl-Al applied at 2000 ppm revealed an inhibition percent of 51 and 100% for P. ultimum and P. mercuriale, respectively. Regarding Hymexazol, the highest inhibition rates were against P. mercuriale (100%) and P. ultimum (90.55%) for 60 ppm. Chinosol revealed to be effective against P. mercuriale for all doses. It was effective against P. ultimum at 50 ppm (90.96%). The highest inhibition rate (86.59%) exhibited by metalaxyl-M was for P. ultimum at 120 ppm. In vivo test showed the efficacy of fosetyl-Al, metalaxyl-M + mancozeb, and chinosol to reduce root browning due to P. ultimum by 55.67%, 44.33%, and 55.67%, respectively, and improved the aerial part sanitary states of seedlings inoculated by P. mercuriale by 60.06, 49.85 and 49.85%, respectively. The chinosol improved the sanitary states of the aerial part of seedlings inoculated by P. ultimum.

Fungal diseases cause a massive reduction in the production of rosemary plants every year. Volatile organic compounds (VOCs) can provide valuable fungal bio-pesticides for practical usage. However, the effect of VOCs on the pathogenic fungi of rosemary is poorly studied. This research characterized some fungal pathogens (Rhizoctonia solani, Fusarium oxysporum, Phytophthora infestans, and Phytophthora citrophthora) isolated from rosemary plants. We studied the inhibitory effect of VOCs, including isovaleric acid, 1-octene-3-ol and 3-octanone on growth and disease incidence of isolated fungi under in vitro and greenhouse conditions. The action of individual VOCs on the growth indices of infected plants was also investigated. 1-octen-3-ol showed the most efficacy percentage and inhibitory effect on mycelial growth at five mg/l concentration. Isovaleric acid decreased fungal growth and disease incidence at 10 mg/l as high as 94.74% and 87.23%, respectively. However, 3-octanone had no significant efficacy percentage and inhibitory effect on mycelial growth. 1-octen-3-ol enhanced the growth of fungal-infected plants to the highest amount, but 3-octanone did not increase the growth of infected plants. The obtained data revealed that the different effects of various VOCs on fungal pathogens are related to different chemical structures and action mechanisms of volatile compounds and the species of fungi involved.

Isolates were identified by molecular and morphological tests, including coleopteran-specific cry genes in the Iranian native Bacillus thuringiensis collection. Spherical and irregular shapes were observed to be the most frequent shapes using Coomassie brilliant blue staining. PCR analysis with universal and specific primer pairs was used to detect coleopteran-specific cry genes such as cry1I, cry3, cry7, cry18, and cry26. All the isolates contained at least one active coleopteran-cry gene, while the most abundant isolates had cry26 and cry18 genes. The patterns of protein size were characterized in addition to their insecticidal activity against third-instar larvae of Tribolium castaneum. Protein profiles produced bands that varied from 14-180 kDa. Four native isolates containing coleopteran-active cry genes displayed higher activity against T. castaneum larvae than B. thuringiensis subspecies galleriae as a reference strain. The median lethal concentration (LC50) of the most pathogenic isolate, PS1078, was 2.72 × 106 spores/ml. Its 16S rDNA gene sequence analysis demonstrated similarity to B. thuringiensiss subspecies galleriae. The characterization of isolates provided useful data for selecting new isolates to expand novel bio-insecticidal products.

Fusarium oxysporum f. sp. albedinis (Foa) is a cosmopolitan soil-borne fungus responsible for the most destructive disease of the date palm tree Phoenix dactylifera L. in Morocco. In the present study, we used aqueous and methanolic root extracts from Punica granatum to evaluate their ability to induce date palm defense against Foa and their antifungal activity. The in vitro treatment of Foa by these extracts showed different inhibitory effects depending on the nature of the extract. The methanolic extract showed significant inhibition of both mycelial growth (51%) and biomass production (86.3%), while the aqueous extract inhibited the sporulation (99.3%) and the spore germination (75.9%) of the pathogen. Moreover, treatment of date palms with methanolic extract has shown a significant increase in phenolic content and peroxidase activity known to be involved in date palm defense against Foa. These preliminary results open a promising field to control date palm Fusarium wilt.

The fungus Ustilago maydis causes common smut disease in corn. Under favorable conditions, it can cause severe damage to corn. In this study, the genetic structure of U. maydis populations in Iran from the most corn-growing regions of seven provinces, including Ardebil, Fars, Isfahan, Kerman, Kermanshah, Khuzestan, and Qazvin, was evaluated using rep-PCR with primers; BOX, ERIC, and REP. Rep-PCR reactions with 109 isolates of U. maydis produced seven distinct clusters consistent with their geographical origin with few exceptions. The results of AMOVA revealed significant genetic differences within and between pathogen populations. The Euclidean similarity coefficient and the UPGMA algorithm indicate five distant clusters based on the disease severity index. The mean comparison of the disease severity index grouped target isolates into 18 clades using the Tukey test. Our findings showed that the pathogenicity assay-based grouping was not consistent with those of the geographical origin of the isolates nor their genetic similarity.

In this study, the effect of five host plants on the biology and food consumption of the fall armyworm Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) was evaluated in Egypt. Developmental periods and weight of different growth stages, percentages of pupation and adult emergence, survival, and nutritional indices were evaluated on maize, castor oil, clover, broad bean, and lettuce. The results showed that the developmental period of S. frugiperda was significantly longer on the broad bean. The pupation percentage of S. frugiperda was significantly affected by the host plant. In contrast, the adult emergence was not significantly different on host plants. Our result also showed maximum weights in food consumption, and frass occurred in the larvae fed on lettuce. While the lowest weights for consumption were observed in larvae on maize and broad bean resulting in minimum frass weights. The highest percentage of approximate digestibility (AD) of the larvae was on broad bean and clover, and the lowest AD was by larvae fed on maize. The highest percentages of conversion of ingested food (ECI) and conversion of digested food (ECD) were observed for larvae fed on maize leaves. The lowest values of ECI and ECD were observed on larvae fed on broad bean leaves. Based on the results, it seems that lettuce, castor, and maize were preferred for S. frugiperda.

Root-knot nematode Meloidogyne javanica is an economically significant plant parasitic nematode in muskmelon farms in Ardestan, Isfahan province, Iran. A two-year experiment was conducted in two muskmelon farms in this region. We assessed the application of 3, 6, and 9 t/ha fresh (unrotten) chicken manure separately or in combination with summer plowing. To evaluate the efficacy of each treatment, the number of galls, egg masses, reproduction factor, plant growth factors, and yield were recorded at harvesting time. The results showed that combining double summer plowing with nine t/ha chicken manure was the most effective treatment for controlling M. javanica. Nematode population indices including: the egg mass number, gall number, total population in root and soil, and reproduction factor, were significantly lower than the control treatment. The application of double plowing with nine t/ha chicken manure treatment caused 83.5%, 79.1%, 80.2%, and 78.3% decreases in egg mass number, gall number, total population per root, and soil, and reproduction factor, respectively. Moreover, total fruit weight and root dry weight in each plot (24 m2) increased by 81.8% and 50.4% compared to the control.

The residues of metsulfuron-methyl in the soil can be a negative factor for the growth of susceptible crops to this herbicide. There are many successful examples of the use of bacteria to increase crop yields and protect plants against stress factors. The purpose of this work was to study the possibility of reducing the phytotoxic effect of metsulfuron-methyl in the soil on sugar beet using plant growth-promoting bacteria. Under greenhouse conditions, sugar beet seeds and bacteria were simultaneously placed in soil previously contaminated with methsulfuron-methyl. The weight of plants, leaf area, amount of proline, malondialdehyde, and flavonoids were measured. Suppression of the growth of young plants and oxidative damage caused by herbicides have been recorded. When sugar beet interacted with bacteria, Pseudomonas protegens DA1.2, oxidative stress caused by herbicide was mitigated, and the mass of plants increased. Treatment with bacteria against the background of herbicidal stress affected the dynamics of the content of flavonoids and proline, which play a role in the anti-stress reactions of plants.

Egyptian broomrape Phelipanche aegyptiaca is a parasitic weed that infests its hosts and feeds on the sap, significantly impacting crop yields. This experiment aims to control the Egyptian broomrape in its seed germination stage and reduce the damage to tomatoes. Fertilizer treatments included urea, ammonium sulfate, and ammonium nitrate at the rate of 150, 250, and 300 kg h-1 respectively, which were applied in three divided stages. Organic herbicide, before transplanting at the rate of six per thousand, and the humic acid plus phosphorus at the rate of two and 60 kg ha-1 in two stages were used in wet soil using calibrated backpack sprayers equipped with a nozzle. Also, four applications of sulfosulfuron (Apiros®, 75% WG) at the rate of 35 g ha-1 at intervals of 30, 40, 50, and 60 days after planting seedlings, and not weeding the Egyptian broomrape (broomrape-infested tomato) were among the other treatments in the experiment. The results revealed that the effect of experimental treatments on the studied traits of tomato and Egyptian broomrape was significant. Application of four stages of sulfosulfuron increased fruit number per plant and yield by 41% and 77%, respectively, compared to the weed-infested control. Herbicide application reduced Egyptian broomrape density by 89% per tomato plant compared to the weed-infested control. Applying sulfosulfuron and humic acid plus phosphorus reduced the dry weight of Egyptian broomrape by 78% and 69%, respectively, compared to the weed-infested control. Also, the relationship between the studied traits in Egyptian broomrape and tomatoes was inconsistent and significant. Based on our results, four applications of sulfosulfuron was recognized as the most effective in reducing the morphological characteristics of Egyptian broomrape and increasing tomato yield in the field. Also, applying two stages of humic acid plus phosphorus effectively reduced broomrape’s adverse effects and increased tomato yield.