The Effects Of Conogethes Punctiferalis On Occurance Of Corn Ear Rot

corn ear rot is a worldwide disease, more common, severe hazard.Cause ear rot and lead to direct production and quality decline, some pathogenic bacteria produce a large number of harmful mycotoxins, a serious threat to human and animal health, pests damage is one of the main factors that cause corn ear rot, asian corn borer, yellow peach moth and cotton bollworm were the main insect pests on corn. In recent years, with the change of the climate and farming system, yellow peach moth occurred serious year by year, because of corn ear rot for corn serious harm, so it is particularly important to protect and control maize ear rot.The effects of co-infestation by yellow peach moth Conogethes punctiferalis (Guenee) and Fusarium verticillioides on the severity of Fusarium ear rot, yield loss and mycotoxin concentrations in kernels were investigated. Corn hybrid Zhengdan 958 was selected as experimental variety, and the corn ears inoculated with neonate larvae of yellow peach moth, F.verticillioides, separately, or yellow peach moth larvae together with F. verticillioides at the silking, blister and milk stages of spring and summer corn, respectively. In order to screen the insecticides and fungicides to control corn ear rot and reduce pest infestation, two insecticides, phoxim, chlorantraniliprole and two fungicides, carbendazim and difenoconazole, were selected to spray for Fusarium ear rot control, separately, or one insecticide mixed one fungicide, at tasseling and silking stage of corn, respectively. Main results are as follows:1. The yellow peach moth infestation significantly aggravated the corn ear rot. Infestation of yellow peach moth and F. verticillioides, not only increased the occurrence of corn ear rot significantly, but also reduced the corn yield at different stages of spring and summer corn ear development. The highest occurrence rate of ear rot was 82.96% and 84.65% when inoculated yellow peach moth together with F.verticillioides in spring and summer corn, respectively.57.52% and 58.70% when inoculated with yellow peach moth only in spring and summer corn,48.85% and 49.85% when inoculated with F. verticillioides only in spring and summer corn, respectively. That the corn ear length shortened, Tip-barren became more longer, the number of the kernels per row decreased, and also other corn yield components were affected, such as 100-seed weight, yield of single ear, when inoculated yellow peach moth together with F. verticillioides. The yield loss per ear was 42.13%,30.43% when inoculated yellow peach moth together with F. verticillioides or yellow peach moth only,21.86% when inoculated with F. verticillioides only, at the silking stage in summer corn. The result demonstrated that the disease incidence, ear-feeding rate and yield loss of summer corn was higher than that of spring corn.2. The effects of injured by yellow peach moth at different developmental stages of corn ear were different on corn ear rot occurrence. The corn ear rot caused by the damage of yellow peach moth was significantly more serious in silking and blister stages than in milk stage. The sequence of ear-feeding rate by yellow peach moth infestation was silking>blister>milk; the yield loss was the highest at silking stage, when inoculated with yellow peach moth and F. verticillioides, separately, or together, the corn yield decreased by 42.13%,22.50%,10.13% at silking, blister or milk stage, respectively, corn yield when inoculated with yellow peach moth together with F. verticillioides.3. Fumonisin was the main mycotoxin in kernels from the ear of Fusarium ear rot Inoculated with F. verticillioides among the mycotoinxs deteceted. The myctoxin accumulation in kernels was the maximum when inoculated yellow peach moth neonate larvae together with F. verticillioides. The accumulation of mycotoxins in kernels was consistent with that the disease incidence oder was silking>blister>milk. The mycotoxin accumulation in kernels was the highest when inoculated at silking stage.4. The selected insecticides and fungicides spray could reduce the incidence of corn ear rot, in which chlorantraniliprole and difenoconazole showed better control effect among the tested pesticides, with 41.55% and 26.67% control efficacy at asseling stage,29.91% and 38.33% at silk stage, respectively. It is showed that all the treatments by the tested insecticides and fungicides could increase the ear length, the number of the kernels per row and 100-seed weight, as well as reduce Tip-barren, and then increase the yield. Overall, insecticide mixed spraying with fungicide exhibited better control effects on corn ear rot compared with the spraying of insecticide or fungicidealone. Spraying of chlorantraniliprole mixed with difenoconazole showed the best control effect on corn ear rot as high as 64.76% of control efficacy,41.55% and 26.67% higher than that of chlorantraniliprole and difenoconazole spraying along, respectively. It increased 37.16% of yield when spraying of chlorantraniliprole mixed with difenoconazole,20.28% and 18.49% higher of than that of chlorantraniliprole and difenoconazole spraying along, separately.5. It was showed that the spraying at different developmental stages of corn ear and the number of spraying times could result in different control effects. Once spraying at both in tasseling and silking stage were recommended, which could obtain the control effect of 67.5% for ear rot with increase of corn yield, compared with the only one spraying in silking stage with the effect of 50%.