Nunhems Netherlands BV PO Box 4005 6080 AA Haelen The Netherlands Tél. : +31 (0) 475-599222 Fax +31 (0) 475-595104 E-mail : nunhems.customerservice.nl@bayer.nl www.nunhems.com Advice for cultivation practice Information provided by Nunhems Netherlands BV in any form whatsoever is without guarantee. Descriptions, recommendations, and illustrations in brochures and leaflets and on the website are based as closely as possible on experiences in tests and in practice. However, Nunhems Netherlands BV does not accept any liability whatsoever on the basis of such information for different results in the cultivated product. The buyer itself must determine whether the goods and information are suitable for the intended growth and/or can be used in the local conditions. Product illustrations All varieties shown were grown under favorable conditions. Identical results are not guaranteed nor implied for all growing conditions. Nunhems BV, 2016. All rights, including property rights, are reserved by Nunhems BV or its affiliates on any matter presented or depicted herein. Leek Diseases Short description of the most important field diseases
Leek Diseases The texts and pictures in this booklet are intended to help the grower identify plant diseases that affect their crops. The information herein is based on general observations. The pictures might give a distorted image of reality. This booklet was compiled with all relevant information available to Nunhems at the time of compilation. The information in this booklet is not to be considered as advice or a recommendation. Nunhems in no event accepts any liability on the basis of the information or pictures in this booklet. Contents 02 Alternaria Porri 03 Puccinia Allii 04 Fusarium Culmorum 05 Phytophthora Porri 06 Stemphylium Botryosum 07 Cladosporium Allii Porri 08 Colletotrichum. Circinans 09 Sclerotium Cepivorum 10 Pseudomonas Syringae 11 Erwinia Carotovora 12 Acrolepiopsis Assectella (Leek moth) 13 Delia Antiqua (Onion Fly) 14 Thrips Tabaci 15 Napomyza gymnostoma (Leek leafminer) 16 Aphids 17 Spider mite. 18 Brown shaft stripes 19 Herbicide Burning 20 Nematodes (Meloidogyne spp, Pratylenchus spp, paratrichodorus spp, trichodorus spp) 21 Yellow stripe virus ALTERNARIA PORRI English : Alternaria Porri Warm and wet conditions ; persistent rains Herbicide damage Foliar disease : White purple spots Leave will crack at damage Affecting leaves will die Use good soils Preventive use of fungicides Frequently scout the field for symptoms Leek Diseases 3
PUCCINIA ALLI (RUST) English : Puccinia Alli (Rust) Sunny day with temperatures above 15 degrees Warm and wet conditions ; persistent rains High humidity Small heaps (patches) of orange spots on the leafs Use healthy plant material Crop rotation Remove crop waste from field Preventive use of fungicides FUSARIUM CULMORUM English : Fusarium Culmorum Unstable growth of the crop Interruption of growth in the first weeks of the plant Old plants 1415 weeks To high EC and to low PH levels Red purple coloured shaft Brown coloured root plate Discoloration in the length direction of the leaf Be careful with organic matter specially the time of application. At least 8 weeks before planting No disturbance in growth Prevent of union fly on plants fields 4 Leek Diseases Leek Diseases 5
PYTOPHTHORA PORRI STEMPHYLIUM BORTRYSOSUM English : Pytophthora Porri No crop rotation Hail and leaf damage Day temperatures above 8 degrees Humid and wet conditions White and dead leaf points White spots with dark green contour on leafs and shaf Spray after rain and hail showers Stable growth of the crop Good drainage system English : Stemphylium bortrysosum Disease survives on dry leaves Unstable growth of the crop Wear and tear disease Small white spots on the leafs Sharped contours of yellow brown spots Harvest on time Vital crop 6 Leek Diseases Leek Diseases 7
CLADOSPORIUM PORRI COLLETOTRICHUM CIRCINANS English : Cladosporium porri In between the 9 and 12 degrees in combination with wet conditions In Autumn it can occur together with Alternaria When the crop closes the field Small oval spots on the leafs The heart of the spot is coloured dark green/ brown with Scout the field When disease occurs spray immediately fungicide English : Colletotrichum circinans Warm and wet conditions Splashing of raindrops can transfer the disease from soil to shaft/leaf Irregular white spots were the shaft/leafs and soils come together In wet conditions black dots can occur in the white spots Sharped contours of yellow brown spots Extensive crop rotation 8 Leek Diseases Leek Diseases 9
SCLEROTIUM CEPIVORUM English : Sclerotium Cepivorum Soil borne disease Wet soils High ph White fungi tissue on the root plate with blackpinned Sclerotium spots Extensive crop rotation When soil is affected the advice is not to grow leek on affected fields PSEUDOMONAS SYRINGAE English : Pseudomonas Syringae Low crop rotation Warm and wet conditions ; persistent rains Carried along in plants Yellow leaf contour Distortion of the leaf Brown and wets spots on the leaf Setback spots of growth in crop Avoid leaf damage Healthy plant material Good crop rotation Not possible to prevent with crop protection 010 Leek Diseases Leek Diseases 011
ERWINIA CAROTOVORA English : Erwinia Carotovora Warm and humid conditions Secondary disease usually after infection of Pseudonomas or Delia Antiqua Infected plants have setback in growth Distortion and fading of the plant Infected plants give a smelly odour ACROLEPIOPSIS ASSECTELLA English : Acrolepiopsis Assectella (leek moth) First attack from half of may Two or three flights per season Leek moth lays eggs around root plate Larvae s eat from the root plate in to the direction of the heart of the plant Yellow and green larvae s inside the shaft Avoid plant damage No irrigation when plants are infected Regularly scouting of the field Placing of pheromone traps Spray of insecticide 012 Leek Diseases Leek Diseases 013
DELIA ANTIQUA English : Delia Antiqua (Onion fly) Every moment after drilling or transplanting White maggots at base of the plant. Sometime also in the heart of the plant Leaves will be yellow and plant will wither THRIPS TABACI English : Thrips Tabaci First development of dry and warm weather Adult thrips are dark brown Larvae in between shaft and leaf Damage of the larvae on the leaves are silverwhite spots More risk of infection of fields out of the wind Spray of insecticide Clean plant material Scout the field Start with spaying when you see the first larvae or adult insect 014 Leek Diseases Leek Diseases 015
NAPOMYZA GYMNOSTOMA English : Napomyza gymnostoma (leek leaf miner) Two generations. One in April May. Second one in Sept Nov. Larvea makes corridors in the length direction of the plant Oxidation makes red colouring of the corridors Symptoms looks similar to red stripes Scout the field Sticky traps Spray with insecticide APHIDS English : Aphids Rare plague in the cultivation of leek Visible on young leaves Aphids excrete honeydew and allure fungi Aphids can transfer other diseases like yellow stripe virus Scout the field Spray with insecticide Irrigation can flush away the Aphids Source Christian Rhoné - Bayer 016 Leek Diseases Leek Diseases 017
SPIDER MITE English : Spider mite Rare plague in the cultivation of leek High temperatures. Optimum development stage is 30 32 degrees and long dry periods White dots on the leaves. Looks like thrips damage. Aphids excrete honeydew and allure fungi Aphids can transfer other diseases like yellow stripe virus Scout the field Spray with insecticide BROWN SHAFT STRIPES English : Brown shaft stripes Explosive unstable growth after transplanting due to combination of fertilizers and high soil temperatures Usually on sandy soils Cells collapse and create red/brown stripes Stable growth Controlled applying of fertilizer 018 Leek Diseases Leek Diseases 019
HERBICIDE BURNING English : Herbicide burning Double appliance of chemical. Overlap Dying of the leafs Weak crop and more susceptible for fungicides Lost yield NEMATODES (Meloidogyne spp, Pratylenchus spp, paratrichodorus spp, trichodorus spp) English : Nematodes Wet conditions of the soil Sandy and silty soils Root rot Knobby roots Roots makes side shoots No overlap Follow guidelines of the label Mechanical weeding Each nematode has it s specific action Growing of Tagetes patula Control of weeds Control your ph level 020 Leek Diseases Leek Diseases 021
NOTES YELLOW STRIPE VIRUS English : Yellow stripe virus Aphids are the host of the virus and can transfer it over to the leek Cold weather develop the disease Yellow stripe that runs along with the leaf vein Spray insecticide Continuous growth 022 Leek Diseases Leek Diseases