Potato Crop Establishment Weed & Disease Solutions

Transcription

1 Potato Crop Establishment Weed & Disease Solutions

2 2 Table of contents Introduction...3 Key diseases in storage Fusarium Dry Rot and Seed Piece Decay...4 Gangrene/Phoma Rot...4 Key diseases at planting Pink Rot...5 Rhizoctonia/Stem Canker/ Black Scurf...5 Silver Scurf...6 Pythium...6 Black Dot...7 Common Scab...7 Powdery Scab...8 Bacterial Wilt...8 Bacterial Soft Rot...9 Black Leg...9 Storage and seed treatments Trial results MAXIM 100FS TECTO RIDOMIL GOLD 480SL In-furrow treatments AMISTAR technology Trial results AMISTAR and RIDOMIL GOLD 480SL Weed control Integrated weed management Key weeds Annual ryegrass Silverleaf Nightshade Blackberry Nightshade Fat Hen Couch Grass Key knockdown herbicides SPRAY.SEED FUSILADE FORTE Key residual herbicides GESAGARD BOXER GOLD... 23

3 Introduction Potato Crop Solutions Program Potato crops are susceptible to a variety of weeds and diseases that can impact on crop yield and quality. This potato crop establishment technical manual aims to provide information that helps growers make informed decisions about Syngenta products, to assist in planning and timely intervention. In all cases, the earliest intervention should be seen as a priority, before weeds or diseases have an opportunity to overtake the crop. Such a proactive approach allows greater opportunity for growers to sustain high crop yields and maximise the return on investment. This manual covers the period from harvesting, ground preparation through to the early crop establishment. Pre-storage/Pre-planting Planting Emergence Up to 6 weeks after planting Seed and soil borne diseases at a 4 and 6 weeks after planting Weed Control (up to 25% emergence) (Prior to emergence) (up to 25% emergence) 15cm or less in height 3

4 4 Key diseases in storage Fusarium Dry Rot and Seed Piece Decay (Fusarium spp.) Symptoms Tuber surface is sunken and wrinkled and rotted tissue is brown or grey to black. White or pink mould may be visible on surface. Internal cavities often develop in rotted tissues and contain white, yellow or pink moulds that are visible when tubers are cut. In storage, blue, black, purple, grey, white, yellow or pink spore masses may form in these cavities. Disease cycle Fusarium Dry Rot is caused by the soil-borne fungus (Fusarium). It survives in decayed plant tissue in the soil. Some infections develop in tubers before harvest, but most occur at harvest through wounds. Small brown lesions appear two to three weeks after harvest and enlarge during storage, taking several months to fully develop. Fusarium Seed Piece Decay is really the same disease. Seed tubers may be infected prior to shipment and rotting in transit or storage. Conditions for development The fungi survive as resistant spores or mycelium in decayed plant tissue in the soil. Although the fungus is dormant below 4 C, infection proceeds fairly rapidly at temperatures above 10 C. Fusarium Seed Piece Decay is more prevalent in soils that stay wet and relatively cool for two to three weeks after planting. Seed Piece Decay will result in poor emergence and plant stand. Gangrene/Phoma Rot (Phoma exigua) Symptoms Phoma Rot is primarily a disease of stored potatoes. The tuber develops depressions resembling thumb marks on the surface with small black pinhead like bodies that contain spores. Disease cycle Tubers contaminated with Phoma exigua spores and spores present in the soil are the primary sources for all stem infections. The spores are washed down into the soil with heavy rainfall or irrigations, or are spread by rain, irrigation or wind to neighbouring plants. The fungus then penetrates the skin of developing tubers where it remains dormant until activated by damage. The spores can also survive for long periods of time in and around storage areas, on bins and equipment, and can be easily spread by drifting dust or when cleaning the storage areas. Conditions for development Any damage (cuts, cracks and bruises etc.) that occurs along with low temperatures (less than 10 C) which prevents the skin from curing.

5 Key diseases at planting Pink Rot (Phytophthora erythroseptica) Symptoms After harvest, infected tubers show dark lines that border the infected and healthy portion of the potato with distinctive black lenticels on the outside of the tuber. Diseased tubers when halved and exposed to the air turn pink in colour after approximately 30 minutes and black after one hour. Disease cycle The Pink Rot fungus survives in the soil as mycelium in decaying plant debris. Pink Rot is soil-borne and can infect roots, stolons and underground stems. Tubers usually become infected through diseased stolons, but infection can also occur through lenticels. The disease is most frequently observed in mature plants approaching harvest. Tubers are usually infected in the field, but the disease can also spread in storage. Conditions for development Plants subjected to water logging from poor drainage, excessive precipitation or irrigation will have a higher incidence of Pink Rot. In wet soils, the pathogen develops over a wide range on temperatures, but is most severe between 20 and 30 C. Rhizoctonia/Stem Canker/Black Scurf (Rhizoctonia solani) Symptoms On young emerging sprouts the growing tip is very susceptible to becoming infected and as a result can be burnt off or girdled prior to emergence. As tubers re-shoot, the new sprouts can also be infected, delaying or preventing shoots from emerging. Rhizoctonia also attacks the stems, stolons and roots. Dark brown lesions or cankers are produced on the lower sections of the developing stems. Damage or girdling to the stolons during tuber initiation can reduce tuber set. Severe infections can result in greater numbers of tubers that are non-uniform in size, misshapen, cracked and or pitted. Disease cycle Black Scurf (also called Rhizoctonia Rot and Stolon Canker), overwinters as sclerotia on infected tubers and in soil, or as mycelium in crop residue. The fungus can be easily transported to new areas by either seed tuber or with the movement of soil by farm machinery. Sclerotia germinate in the spring and invade sprouts or stems. Roots and stolons are invaded as they develop throughout the growing season. Maximum development can continue to occur after the plants have died off while the tubers remain in the ground. Conditions for development Cool, moist soils at 12.5 to 16 C are optimal for disease development. The pathogen population will generally increase if cropping rotation intervals are short or continuous. 5

6 6 Key diseases at planting (cont.) Silver Scurf (Helminthosporium solani) Symptoms Tubers after harvest in storage develop small, light brown circular spots with indistinct borders. A silvery sheen that can cover large areas appears, especially when the tuber surface is wet. Coloured varieties usually show more visible signs. Badly infected potatoes will shrink due to loss of moisture and will eventually be covered by a sooty, black mould. Disease cycle Silver Scurf overwinters in soil, on crop residues or in harvested tubers. The fungus sporulates on infected seed pieces and then the spores wash onto new tubers either at or after planting. Infection takes place through lenticels and periderm before the tubers are dug. Conditions for development The longer mature tubers remain in the soil, the more severe the problem becomes. Fluctuations in storage temperatures at high relative humidity (>90%) can result in condensation on tuber surfaces, allowing the fungus to sporulate and colonise new tissue. Sporulation is more abundant on young lesions than old ones. Pythium (Pythium ultimum and Pythium spp.) Symptoms On the tubers, discoloured and water-soaked areas appear around a bruise or wound. Internally infected tissue is clearly separated from healthy tissue by a dark boundary line. Rotted tissue is spongy and extremely watery, ranging in colour from grey to brown to black. Disease cycle Pythium survives in the soil and enters the tubers only through wounds. Infection usually occurs during harvest or grading and less frequently at planting. The fungus is a water mould and needs free water to spread and infect tubers. Conditions for development Soil temperatures above 19 C at harvest, as well as extremely wet conditions, followed by a short period of dryness during tuber maturation, increases the incidence for Pythium Rot. Relatively high temperatures and poor ventilation in storage also promote infection.

7 Key diseases at planting (cont.) Black Dot (Colletotrichum coccodes) Symptoms Infected stems may wilt completely or die back. Many tiny, black sclerotia appear on senescent tissue including roots, stolons, stems and tubers, especially as the growing season draws to a close. Dark, sunken, necrotic lesions may also appear on stems, petioles and veins. Symptoms on the tubers often resemble those of Silver Scurf and appear to be greyish-brown lesions with sclerotia that develop on tubers. Disease cycle Black Dot can survive for long periods in the form of sclerotia on and within the tubers and also in plant debris in the field. In addition to potatoes, this fungus also invades several vegetable species in the potato family and a few weed species. When conditions are favourable, the fungus invades underground stem tissue and moves upward in the plant. Airborne spores also infect the foliage, especially when tissue is injured by windblown sand and the disease progresses downward into the stem and roots. Conditions for development Colletotrichum is considered a weak pathogen that attacks plants under stress conditions, often accompanied by one or more other disease pathogens. This disease is more severe in light sandy soils, with minimal nitrogen, poor drainage, and high temperatures (greater than 32 C). Common Scab (Streptomyces scabies) Symptoms Common Scab symptoms on the tubers can appear as either shallow or deep lesions (scabs). Shallow lesions on the tuber appear roughly circular in shape, raised and tan to brown in colour. A superficial layer of corky tissue occasionally occurs instead of the circular lesions. In other cases, deep-pitted dark brown to black lesions between one to 10 mm deep may develop on the surface surrounded by corky material while the tissue underneath appears straw coloured and translucent. Disease cycle Common Scab is introduced into the soil on seed potatoes and survives indefinitely once the soil is contaminated. The organism can survive on decaying plant debris and is spread by wind, water, or by equipment carrying soil. Newly forming tubers become infected through immature lenticels. Lesions on infected tubers expand and increase in severity throughout the season. Conditions for development Warm, dry soil favours this disease. Common Scab is also favoured by soils with a ph from 5.5 to 8.0 and generally as ph increases so too does the severity of Common Scab. Continuous cropping with potatoes and coarse soils that dry out quickly can also promote this disease. 7

8 8 Key diseases at planting (cont.) Powdery Scab (Spongospora subterranea) Symptoms Powdery Scab infected plant roots may have small light coloured galls or warts between one to 10 mm in diameter. Infected tubers may have present blister like swellings up to 10 mm in diameter on the surface. These scabs when exposed to air after harvest will change to a browny colour, powdery in appearance. Disease cycle Powdery Scab can survive as spores known as sporeballs in the soil for several years in a dormant state. The roots and stolons can be infected at any time. Tubers however can only be infected during the critical period of tuber initiation when the lenticels are forming in the tuber skin. The fungus infects tubers through these lenticels. This susceptible period lasts for approximately four to six weeks after tuber initiation. Conditions for development Powdery Scab spores will only germinate in the presence of the host producing a zoospore, which is only mobile in water saturated soil. The zoospore then infect the developing roots and stolons, where they multiply to produce more spores. The disease cycle can occur several times in successive periods of cool (10 to 20 C, optimum 15 C) wet conditions. Bacterial Wilt (Ralstonia solanacearum formerly Pseudomonas solanacearum) Symptoms Bacterial Wilt affected plants will often have yellowing leaves that roll upwards and inwards, wilt during the day with recovery at night. There is yellowing and some stunting of the plant until eventually, the plant dies. The stems, roots and stolons can show a brown discolouration and when cut, a white slimy bacterial mass oozes from the tissue, making this different from other fungal wilts. Tubers often exhibit brown to greyish areas on the surface, particularly near the eyes. Disease cycle The bacteria can survive for up to three years in bare fallow soil and even longer in association with plant debris or alternative hosts. The bacteria enter the plant generally through wound sites (root emergence sites, mechanical or insect damage) and move around the plant vascular system through the roots, eventually infecting the tuber through the stolon. Plants can also be infected by seed tubers with latent (no visual signs of the disease) infections. Conditions for development This disease can develop favourably under a wide range of conditions.

9 Key diseases at planting (cont.) Bacterial Soft Rot (Pectobacterium atrosepticum, Pectobacterium carotovorum subsp. arotovorum, and several species of Dickeya spp. including D. dianthicola, Dickeya solani) Symptoms With Bacterial Soft Rot, tubers may have yellowy brown, circular water soaked lesions around the lenticels, a soft depressed area. The tissue becomes slimy and is odourless. An odour usually develops when secondary bacteria colonise the decaying tissue. Disease cycle The bacteria that causes Bacterial Soft Rot can be found in most soils and can also be present at varying levels on most seed tubers. Infections generally occur when the mother tuber breaks down, releasing the bacteria into the soil to infect developing tubers when the tuber surface is wet in low oxygen (anaerobic) conditions (e.g. waterlogged soils). The bacteria generally enter through the lenticels or through wound sites on the tubers. In storage, Bacterial Soft Rot is generally not a problem unless the tubers are not dried correctly after harvest, or they become wet during storage. Conditions for development Wet, anaerobic conditions are most suitable for the development of Bacterial Soft Rot. Bacterial Soft Rot can develop at temperatures between 5 to 37 C with the optimum temperature range being between 25 to 30 C. Black Leg (Erwinia spp.) Pectobacterium carotovorum subsp. Carotovorum) Symptoms Black Leg moves from the rotting seed piece into the stems causing a blackening of the stems, soft rotting of plant tissue that may just be visible above the soil surface, these infected stems can have a discoloured vascular system. The tops of the plant will show pale green or yellow foliage, the tips of upper leaves can appear to be red in colour. Leaf margins can roll upwards (cupped). Tubers that become infected with Black Leg develop a slight vascular discolouration at the stolon end, or soft rotting of the entire tuber. Disease cycle The primary cause of Black Leg is diseased seed stock, which can be infected internally or carry the disease on the skin. As the seed piece decays a large number of spores can be released into the soil, which in turn can infect the developing daughter tuber either through the stolons, wound sites or through the lenticels. In storage, Bacterial Soft Rot is generally not a problem unless the tubers are not dried correctly after harvest or they become wet during storage. Conditions for development The bacteria can spread considerable distance in soil water and is favoured by cool wet soils at the time of planting. The optimum temperature for disease development is between 18 to 19 C. 9

10 10 Storage and seed treatments Seed treatment trial results Efficacy of MAXIM 100 FS, Tecto SC and Fungaflor 750 SG on Fusarium Dry Rot incidence after four months of cold storage, Lenswood, South Australia: cv Coliban (Report: ). Efficacy of MAXIM 100 FS, Tecto SC and Fungaflor 750 SG on Fusarium Dry Rot incidence 43 days of storage, Devonport, Tasmania, cv Nicola (Report: SYN07236) a Fusarium Dry Rot % severity a c b Disease severity rating index b d b d 0 Untreated Control MAXIM 100 FS Tectco 450 SC Fungaflor 750 WSP 0 Untreated Control MAXIM 100 FS Tectco 450 SC Fungaflor 750 WSP

11 Storage and seed treatments MAXIM 100FS MAXIM 100FS is a seed treatment that offers growers control of the following seed-borne diseases in potatoes: Seed borne Black Dot (Colletotrichum coccodes), Fusarium Dry Rot (Fusarium spp.), Black Scurf (Rhizoctonia solani) and Silver Scurf (Helminthosporium solani) and the suppression of seed borne Common Scab (Streptomyces spp.), providing potato growers with the only registered management option for the major seed potato soil and seed borne diseases. MAXIM 100FS can now also be applied prior to storage of seed potatoes, offering protection of fusarium in storage and also activity on soil and seed bourne diseases in the field after planting, offering growers greater flexibility in when they can apply MAXIM 100FS. Key Features Excellent protection against a range of seed-borne diseases Healthy tubers and uniform crop establishment results in higher marketable yields Easy to use low dose rate saving time and expense Minimal impact on the environment Increased marketable yields when combined with AMISTAR Technology in-furrow Product Profile Active Ingredient Formulation 100 g/l fludioxonil Fungicide Group GROUP 12 Target Disease Activity Packaging Application Rate Withholding Period Suspension concentrate Application and Use Apply MAXIM 100FS to the seed potato prior to storage or prior to planting DO NOT apply to seed potatoes prior to planting if an application was made prior to storage Ensure even distribution over the seed Ensure industry best practices are followed to minimise development and severity of storage diseases Seed borne Black Dot (Colletotrichum coccodes), Fusarium Dry Rot (Fusarium spp.), Black Scurf (Rhizoctonia solani) and Silver Scurf (Helminthosporium solani) and the suppression of seed borne Common Scab (Streptomyces spp.) Seed piece protectant, inhibiting spore germination 5 L 250 ml/tonne of seed Not required when used as directed Seed Treatment Mix the required quantity of MAXIM 100FS with only sufficient water (maximum of 3 L/tonne of seed) to ensure thorough coverage. Ensure even distribution over the seed. Ensure that the potato seed is thoroughly dried immediately after application and before planting. Also avoid using MAXIM 100FS if the conditions or seed quality favour the development of bacterial rots. Planting Mix the required quantity of MAXIM 100FS with water to make up a total volume not exceeding 8 to 10 L/t of seed. Use the minimum water required to ensure thorough coverage. Ensure constant agitation of the spray tank mix during spraying. 11

12 12 Storage and seed treatments TECTO TECTO is a broad spectrum seed treatment for potatoes in storage, which provides excellent residual protection for a range of diseases (as stated on the label). Apply TECTO after harvest, preferably as potatoes move along a conveyer and before storage. Extra care should be taken to ensure thorough application to the tuber. Key Features Excellent control of post-harvest pathogens Disease free potatoes with a clear, clean skin No irritation to field and packing house workers No taste, odour or unsightly residue issues Low toxicity and low environmental impact Product Profile Active Ingredient 500 g/l thiabendazole Formulation Suspension concentrate Fungicide Group GROUP 1 Target Disease Dry Rot, Gangrene and Silver Scurf Activity Seed piece protectant Packaging 5 L Application Rate Mix 1 L of TECTO to 22 L of water and apply 2 L of solution in a mist per one tonne of potatoes Withholding Period Not required when used as directed

13 In-furrow treatments RIDOMIL GOLD 480SL RIDOMIL GOLD 480SL is a systemic (xylem mobile) fungicide used to control certain diseases caused by the Oomycetes class of fungi in a range of crops including pink rot in potatoes. RIDOMIL GOLD 480SL is readily absorbed by the roots offering systemic (xylem mobility) movement within the plant that protects the developing potato plant against attack from disease under varied weather conditions. Key Features Unique Metalaxyl-M technology Increased yields due to protection against Pink Rot Outstanding performance, particularly in wet conditions An excellent track record with proven results in all seasonal conditions Product Profile Active Ingredient 480 g/l metalaxyl-m Formulation Soluble liquid Fungicide Group GROUP 4 Target Disease Pink Rot (Phytophthora erythroseptica) Activity Systemic. Prevents disease developing from within the plant Packaging 5 L Application Rate 8 ml/100 m of row Withholding Period Not required when used as directed Application and use Apply once as an in furrow spray; mount the nozzle so that the spray is directed in a narrow cm band just before the seed is covered. Apply in 1 3 L of water per 100 m of row ensuring good coverage of the seed piece. Follow-up with two applications of RIDOMIL GOLD MZ at 14 day intervals, commencing four to six weeks after planting. The foliar applications of RIDOMIL GOLD MZ will top up the levels of metalaxyl-m in the plant and soil. RIDOMIL GOLD 480SL is compatible with AMISTAR 250 SC and can be applied using an AMISTAR in furrow application set up. 13

14 14 In-furrow treatments AMISTAR Technology AMISTAR Technology works by inhibiting the ability of organisms in fungal disease to convert nutrients into energy. Without energy, the fungus dies and no longer damages the crop. Unlike most fungicides, it is highly active against four major classes of fungal plant diseases: leaf spots, powdery mildew, rusts and mould. When used as an infurrow fungicide in potatoes, AMISTAR 250 SC is registered for the control of Black Scurf and suppression of Silver Scurf. Key Features Long lasting preventative disease control Flexible timing as in furrow and foliar application Low rates of application means easier management and handling of product Excellent compatibility with a wide range of fungicides and insecticides A unique mode of action with no known cross resistance Application and Use Apply once as an in furrow spray at planting. Mount the spray nozzle so the spray is directed into the furrow as a 15 to 20 cm band just before the seed is covered. Use the higher rate of AMISTAR 250 SC where higher levels of disease occur. Use the lower rate where lower levels of disease occur or where less disease control is required. Apply in 1 to 3 L of water/100 m of row. Product Profile Active Ingredient Formulation 250 g/l azoxystrobin Fungicide Group GROUP 11 Target Disease Activity Packaging Application Rate Withholding Period Suspension concentrate Soil borne: Black Scurf (Rhizoctonia solani) Suppression of Silver Scurf (Helminthosporium solani) Ensure the water volume used is not so high as to wash off any seed treatments previously applied to seed. DO NOT apply AMISTAR 250 SC if conditions or seed quality favour bacterial rots as these diseases may be aggravated if seed comes into contact with additional moisture. DO NOT apply AMISTAR 250 SC if planting in hot, sandy soils as bacterial rots may be aggravate. Translaminar activity. Controls disease from inside the plant 5 L 5 to 10 ml/100 m of row Not required when used as directed

15 In-furrow treatment trial results Amistar in-furrow application. Potato, Australia, 2003 FSF025A4-2004AU Tim Kimptom VIC 2003 Russett burbank (Planted 17 Dec 2003) % Incidence of Black Scurf (Rhizoctonia solani) a Untreated b Black Scarf. Rhizoctonia Solani b AMISTAR 150 AMISTAR 300 AMISTAR 450 b b MAXIM 2.5/100 kg + AMISTAR 250 Columns indicated with letters the same are not significantly different at the 5% level LSD test b MAXIM 2.5 g ai/ The following results come from a trial conducted by Serve-Ag Research in Tasmania during the 2002/03 season. T/ha d Untreated Marketable Yield** Assessment at harvest bcd AMISTAR 750g/ha cd MAXIM MAXIM 25 ml/100 kg 25 ml/100 kg + AMISTAR 750 g/ha Return on investment is critical to maintain a profitable potato operation. At a price of $200/t a yield increase of 17.2t/ha equates to $3,440 more income. a Amistar in-furrow application. Potato, Australia, 2003 FSF025A4-2004AU Tim Kimptom VIC 2003 Russett burbank (Planted 17 Dec 2003) Crop Establishment (% plant emergence) at 43 Days After Planting, Lameroo 2005 (n.s at P=0.05) 60 a % Incidence of Silver Scurf (H solani) Untreated bc cd cd AMISTAR 150 AMISTAR 300 AMISTAR 450 d MAXIM 2.5/100 kg + AMISTAR 250 d MAXIM 2.5 g ai/ Untreated MAXIM 100 AMISTAR 250 AMISTAR 250 AMISTAR 250 FS 250 ml/t SC 5 ml/100 m SC 10 ml/100 m SC 50 ml/100 m MAXIM 100 FS 250 SC Mini-tubers Rizolex liquid 400 ml/t Columns indicated with letters the same are not significantly different at the 5% level LSD test 15

16 16 In-furrow and seed treatments Getting the best out of your AMISTAR technology and RIDOMIL GOLD 480SL in-furrow applications One of the major benefits of using in-furrow fungicide application either on their own or in combination with a potato seed treatment like MAXIM 100FS is that you provide protection against fungal disease in soil protecting the stolons, roots, stems and tubers. Offering this soil protection can enhance the evenness of emergence, tuber size, clean skin finish, processing quality, visual appearance and marketable yields. Through Syngenta s excellence in in-furrow application, specific nozzles have been developed specifically to apply in-furrow fungicides. Syngenta best practice recommends two nozzles be used to apply AMISTAR Technology and RIDOMIL GOLD 480SL (right). AMISTAR Technology and RIDOMIL GOLD 480SL In-Furrow Treatment Effective Zone MAXIM Seed Treatment Effective Zone The FRONT Nozzle on the planter is positioned at the front of the planter. This 20 nozzle applies a thin band of AMISTAR Technology and RIDOMIL GOLD 480SL to the bottom of the furrow before the seed piece is dropped in to the furrow, in contact with the treated soil. The REAR nozzle is positioned to apply a 70 spray band to the bow wave of soil being hilled over the row to cover the seed piece. Correct positioning of the nozzle should achieve an even mix of AMISTAR Technology and RIDOMIL GOLD 480SL through the mould, giving excellent protection of stolons, roots, shoots and developing daughter tubers Syngenta AMISTAR In-Furrow Nozzle Set Hollow cone AZ IF is a 20º spray angle (front) AZ IF is a 70º spray angle (rear) APPLICATION CHART Pressure Bar PSI Flow (L/min) Best Practice: Hints and Tips Equipment 1. Agitation (L/min) at least 10% of combined tank capacity (L) + nozzle output (L/min). a. eg. a 100 L tank and 4 nozzles applying 0.8 L/min total, require a pump with a minimum output of 10.8 L/min, at normal operating pressure. 2. As small bore pipes as possible for spray lines. 3. Bayonet caps for easy nozzle removal mesh x2 wire filters in circulation system. a. No nozzle filters. 5. Drain Taps to empty system. In Field 1. Use tap water only. 2. Calculate last load so approx L spray mix remains in tank at end of day. 3. Drain spray mix (10 L) each evening. Store in marked container. 4. Wash out system, clean all nozzles, clean all filters, leave nozzles in bucket of water overnight and leave with water in circulation system. 5. Check spray first thing in morning with clean water. 6. Mix fresh load each morning. 7. Shake yesterday s remnants well. Add little by little to new mix, after the first half hour s work. 8. Agitate at all times (during breaks) with engine running. Will flatten tractor battery in 10 minutes if not.

17 Weed control The benefits of effective weed control are many, including better use of available nutrients by the crop, resulting in increased yields and profits. The underlying principle of weed control in potato crops is that weed competition can result in a reduction in marketable yield and quality. For each 10 per cent increase in weed biomass as a result of annual weeds, potatoes can incur a 12 per cent decrease in yield (Nelson and Thoreson 1981) The critical period for weed removal in potatoes is around four to six weeks after planting In the Australian market there are very few herbicide options for selective broadleaf and grass weed control that are suitable for use during early crop development and prior to row closure. Today, greater importance is placed on limiting the risk of herbicide resistance for potato growers. Herbicides with new active ingredients are essential for resistance management, to broaden the spectrum of weeds controlled and to deliver choice and adaptability. Over reliance on any one particular herbicide group will not only select for resistance, but may also change the weed spectrum, thereby allowing a weed or weed species not controlled by that particular herbicide group, to become dominant. This means the adoption and implementation of effective, long term, weed control strategies that have an integrated and planned approach and do not rely solely on the use of herbicides to control weeds. BOXER GOLD was 5 L/Ha Photo: Michael Harding, gronomist Elders Virginia An integrated weed management program includes Controlling weeds in the rotational crops or during fallow periods using herbicides with different modes of action Using knockdown herbicides before establishing the crop Where possible, using mechanical weed control before row closure Sowing vigorous crops that compete strongly and quickly close the row over to reduce the amount of light reaching germinating weeds Maintaining a healthy crop stand that can out compete weeds Sencor 480 SC was 400 ml/ha Applying knockdown herbicides as the crop is in the senescent stage to control weed growth and for ease of harvest Rotating potato crops with pasture or other crops that allow easy control of major potato weeds Avoiding use of contaminated seed or unclean machinery. These are often the cause of introduced weed seed Pre-planting management can greatly help to reduce the weed seed bank. Before planting, form seedbeds and pre-irrigate to encourage weed seeds to germinate, resulting in an easier weed kill. 17

18 18 Key weeds Annual Ryegrass (Lolium rigidum) Factors that make Annual Ryegrass a major weed Annual Ryegrass produces an extremely high number of seeds per plant Survivors of control measures can tiller well and produce high numbers of viable seed These factors result in large seedbanks and, subsequently, high weed numbers at emergence. Dense stands (greater than 100 plants/m 2 ) can produce up to 45,000 seeds/m 2 under ideal conditions Newly formed Annual Ryegrass seeds are typically dormant, with seeds losing dormancy during the first six months after dispersal Many populations of Annual Ryegrass have developed resistance to both selective and non-selective herbicides In 2013 in Australia, Annual Ryegrass had developed resistance to seven herbicide mode-of-action (MOA) Groups (A, B, C, D, L, M and Q) Repeated use of herbicides from the same MOA group (particularly the high-risk Groups A and B) is likely to select for herbicide resistant individuals that will produce large numbers of seeds and quickly become a serious and significant weed problem. Ideal germination Conditions Autumn and winter rain events of at least 20 mm and seed located at a depth of 20 mm in the soil. Germination reduces with increasing depth of seed, ceasing at about 100 mm The optimum temperature for germination of Annual Ryegrass is much lower for buried seeds in darkness (11 C) compared with seeds in the light (27 C) 75 to 80 per cent of the seed will germinate on the first or second significant autumn rain 12 to 23 per cent of seed germinates after June (McGowan, 1970). Spike initiation occurs after a cold requirement has been satisfied and the day length increases to more than 8 hours Biological control A fungal pathogen (Pyrenophora seminiperda) has been isolated and identified as a potential bioherbicide for grass weeds in the future. The fungus infects the seed, reducing germination, emergence and seedling vigour. Physical control Cultivation and mowing can be implemented for several consecutive years prior to planting to reduce the seed bank. Conventional control Herbicide resistance developed rapidly in Annual Ryegrass because of high genetic variability, high reproduction by outcrossing (cross pollination by wind allows gene transfer from resistant to susceptible plants via pollen). There are now Annual Ryegrass populations resistant to almost all herbicides available for its control.

19 Key weeds Silverleaf Nightshade (Solanum elaeagnifolium) Factors that make Silverleaf Nightshade a major weed Silverleaf Nightshade belongs to the genus solanum which includes potatoes and tomatoes Silverleaf Nightshade is a declared noxious weed in New South Wales, Victoria and South Australia Silverleaf Nightshade can reproduce from roots or seeds. Seeds are produced in four to eight weeks after flowering Cultivation cuts the roots into pieces and aids the transport of material that could form new infestations Seed bank estimates range from 1200 to m 2, although Australian records indicate 4000 m 2 is more likely Seeds have a high viability and persist for several years, but generally require warmth and rainfall to germinate Seeds are dispersed primarily by livestock, but can also be spread by water, birds, vehicles and machinery. Ideal germination conditions Silverleaf Nightshade prefers temperate regions with annual rainfall between 250 to 600 mm. It will grow in most soil types and favours disturbed areas such as cultivated paddocks and roadsides. It is sensitive to frost, which will kill new shoots, but is highly drought resistant due to its extensive root system. Biological control Due to Silverleaf Nightshade being closely related to tomatoes, eggplant, capsicum and tobacco, biological agents are not considered an option. Conventional control Silverleaf Nightshade infestations cannot be successfully eradicated with a single herbicide application. Foliar growth can be controlled in season, however regrowth can occur later in the same season or in the next season from the same rootbank. Maintaining a herbicide program over several years is required to run down an established Silverleaf Nightshade problem due to the extreme persistence of seeds and roots in soil. Broadleaf, contact and pre-emergent herbicides are effective if applied carefully before seed is set. Physical control Ensure any machinery, hay and livestock brought into cropping paddocks are weed free. Also ensure control measures are implemented on areas around your planned cropping area e.g. roadsides, surrounding paddocks etc. 19

20 20 Key weeds Blackberry Nightshade (Solanum nigrum) Factors that make Blackberry Nightshade a major weed Blackberry Nightshade belongs to the genus solanum which includes potatoes and tomatoes Blackberry Nightshade (Solanum nigrum) is regarded as an environmental weed in Victoria, Western Australia, New South Wales, Queensland and the Northern Territory Seed bank estimates range from 1200 to m 2, although Australian records indicate 4000 m 2 is more likely Seeds have a high viability and persist for several years, but generally require warmth and rainfall to germinate Seeds are dispersed primarily by livestock, but can also be spread by water, birds, vehicles and machinery Physical control Cultivation and mowing can be used to prevent seed production for several years. Note, that Blackberry Nightshade has a tough woody stem and is best removed whole including the roots. When hand pulling, remove from the paddock if in flower. Conventional control Blackberry Nightshade is susceptible to herbicidal control, although it has a waxy leaf and a thick stem that prevents herbicide uptake. Herbicide performance is increased with the use of a penetrant adjuvant. Physical control Ensure any machinery, hay and livestock brought into cropping paddocks are weed free. Also ensure control measures are implemented on areas around your planned cropping area e.g. roadsides, surrounding paddocks etc. Ideal germination conditions Blackberry Nightshade is considered to be an annual or short-lived perennial. It emerges in autumn and winter and can last through summer to the following season and live as a perennial plant. Biological control There is no known biological control. Grazing is not recommended as fruit can be toxic to livestock.

21 Key weeds Fat Hen (Chenopodium album) Factors that make Fat Hen a major weed Fat Hen grows faster and absorbs nutrients more efficiently than any crop and can grow in almost any soil Plants have produced 500,000 seeds and seeds have been known to survive for 30 to 40 years in the soil Ideal germination and establishment conditions Fat Hen is a plant that grows well under a wide range of environmental conditions (it does however dislike shady environments). Fat Hen prefers moderately fertile soil and tolerates ph in the range 4.5 to 8.3. It can grow year round. In the northern areas it tends to be a winter weed, but in the southern areas it is more a summer weed. Physical control Manual removal, particularly when plants are young, is effective because Fat Hen generally produces a shallow root system. Mulching is an excellent method to prevent germinating seeds from establishing. Cultivation may be useful, again because the plant s shallow root system is easily dislodged from the soil and the plant quickly dries out in warm weather. Conventional control Broadleaf, contact and pre-emergent herbicides are effective when applied carefully before seed is set. Biological control Fat Hen is vulnerable to leaf miners (small insects that eat its leaves). It does not compete well with other groundcovers and suppressing it with covercrops can help. 21

22 22 Key weeds Couch Grass (Cynodon dactylon) Factors that make Couch Grass a major weed The lack of regular cultivation and this weed s ability to spread its tough scaly rhizomes and branching stolons, make Couch Grass a very difficult weed to control Because of its rapid growth and aggressive growth habit, Couch Grass is categorised as a noxious weed in some states Couch Grass will effectively smother low vigour crops Apical dominance makes it hard to control with herbicides Physical control Hand removal must be complete or the plants can spread from root sections left over in the soil. Cultivation can spread this grass and is not recommended. Conventional control Grass selective herbicides are effective on Couch Grass. Best results come from a Double Knock spray program of SPRAY.SEED (non-selective) followed by FUSILADE FORTE (selective herbicide). Ideal germination and establishment conditions Couch Grass can grow all year round if water is available, but in general, it is a summer weed that thrives on irrigation. It spreads rapidly by seed and runners and even small fragments of roots. Biological control There is no effective biological control of Couch Grass. Couch can be grazed heavily but will continue to survive into the following season, spreading from the root system.

23 Key knockdown herbicides SPRAY.SEED Application and Use Product Profile Key Features Controls most annual grasses and broadleaved weeds Unrivalled knockdown speed Rainfast within minutes Compatible with a range of herbicides (BOXER GOLD, GESAGARD, metribuzin etc) Good activity on hard to kill weeds No effect on crop emergence Alternative chemistry to glyphosate to aid in resistance management For best results and to reduce the chance of off target damage, only apply SPRAY.SEED with a well calibrated ground application sprayer Apply with clean water at rates between 50 to 200 L/ha. The volume of water is determined by the size of the target weeds. Use a wetting agent when required as per the label to ensure even coverage Ideal application timing is when 10 to 25 per cent of the potato shoots have emerged following hilling up. Emerged shoots will suffer marginal leaf burn but will recover quickly Active Ingredient Formulation Herbicide Group Target Weeds Mode of Action Packaging Application Rate 135 g/l paraquat and 115 g/l diquat Aqueous solution GROUP L Grass and broadleaf weeds (as per label) Inhibitor of photosynthesis at photosystem I 20, 100 and 1000 L 2.4 to 3.3 L/ha at pre-plant and post-plant stage 3.2 L/ha for weed destruction before digging (not to be used for desiccation of the potato crop) Withholding Period Not required when used as directed FUSILADE FORTE Key Features (cont.) Product Profile Key Features Controls a wide range of annual grasses including Annual Ryegrass, Annual Phalaris, Barley Grass, Barnyard Grass, Brome Grass, Crowsfoot Grass, Liverseed Grass, Stink Grass, Summer Grass, Volunteer Cereals, Wild Oats, seedlings of Couch Grass, English Couch, Johnson Grass, Water Couch and plants of Bent Grass, Couch Grass, English Couch, Johnson Grass, Kikuyu Grass, Paspalum, Water Couch re-established from seed or fragmented stems Well proven over many years High level of crop safety Stops weed growth in two days Rainfast in one hour Application and Use Apply using 100 to 200 L/ha water Use higher water volumes if weed growth is dense or where crop is shielding weeds The potatoes must be 15 cm or less in height Active Ingredient Formulation Herbicide Group Target Weeds Mode of Action Packaging Application Rate 128 g/l fluazifop-p present as the butyl ester Emulsifiable concentrate GROUP A Grass weeds (as per label) Inhibitor of lipid synthesis (acetyl CoA carboxylase inhibitors) 5 and 20 L 820 ml to 3.3 L/ha Withholding Period 10 weeks 23

24 24 Key residual herbicides GESAGARD Application and Use Product Profile Key Features Key weeds: Less than 4 true leaves and pre-emergent: Amaranth (Powell s, Slim and Redroot), Amsinckia, Blackberry Nightshade, Capeweed, Charlock, Chickweed, Corn Gromwell, Deadnettle, Fumitory (Common, White and Dense Flowered), Fat Hen, Hedge Mustard, Hexham Scent, Indian Hedge Mustard, Lesser Nettle, Mountain Sorrel, Rough Poppy, Three Cornered Jack, Wild Radish. Pre-emergent suppression of Annual Ryegrass, Barnyard Grass, Prairie Grass and Summer Grass Apply GESAGARD prior to crop emergence using a ground sprayer fitted with flat fan nozzles. Ensure good coverage and aim to apply 50 to 110 L/ha of spray solution. Use the lower rate on light soils and the higher rate on heavy soils. Active Ingredient Formulation Herbicide Group Target Weeds Mode of Action Packaging Application Rate 500 g/l prometryn Suspension concentrate GROUP C Broadleaf weeds and suppression of certain grass weeds (as per label) Inhibitor of photosynthesis at photosystem II 20 L 2.3 to 3.3 L/ha (Qld, NSW, Vic, Tas, WA only) Short residual control of weeds to aid in crop establishment Withholding Period Not required when used as directed Flexible application timing to suit pre-emergent control Excellent control of weeds with no effect on the crop or yield Proven performance under all conditions Compatible with knockdown herbicides and other pre-emergent herbicides including SPRAY.SEED and BOXER GOLD

25 Key residual herbicides BOXER GOLD Key Features Key weeds: Annual Ryegrass including control of Group D resistant populations, Barnyard Grass, Blackberry Nightshade, Fat Hen, Fumitory, Glossy Nightshade, Redroot Amaranth, Summer Grass, Toad Rush. Suppression of Common Thornapple and Fierce Thornapple Ideal for resistance management Very versatile simple recommendations, tank-mixing and application timing Application and Use Apply after planting, after the first cultivation, but no later than 25 per cent potato shoot emergence. Application should be made to moist soil. Good soil moisture in the top 3 to 5 cm of soil is required for weed uptake to occur. Drying of the top soil can result in less effective weed control. Cultivation after herbicide application may be detrimental to weed control and crop safety if it results in the herbicide being unevenly distributed in the soil. Crop yellowing may occur where BOXER GOLD is used on soils that have a low organic matter content and which contain more than 60 per cent of fines and silt (crops will recover fully). On these soil types, use rates of BOXER GOLD towards the lower end of the rate range. DO NOT apply to potato fields where slopes exceed 4% DO NOT apply BOXER GOLD more than once per crop. DO NOT apply BOXER GOLD after 25 per cent potato shoot emergence. BOXER GOLD may be tank mixed with registered knockdown herbicide (eg SPRAY.SEED) at recommended label rates and timing for control of additional weeds. Product Profile Good levels of crop safety across all potato varieties and all farm soil types when used as directed Good compatibility with, glyphosate, oxyfluorfen, SPRAY.SEED, GESAGARD and metribuzin and with any one of the following insecticides: alpha cypermethrin, bifenthrin, chlorpyriphos, dimethoate and KARATE ZEON Insecticide. Active ingredient Formulation Herbicide Group Target Weeds Mode of action Packaging Application rate Withholding period 800 g/l prosulfocarb and 120 g/l S-Metolachlor Emulsifiable concentrate Group J and Group K 4 to 5 L/ha: Annual Ryegrass including control of Group D resistant populations, Barnyard Grass, Blackberry Nightshade, Fat Hen, Fumitory, Glossy Nightshade, Redroot Amaranth, Summer Grass, Toad Rush, Suppression of Common Thornapple, Fierce Thornapple 5 L/ha: Capeweed Inhibitors of cell division / inhibitors of very long chain fatty acids (VLCFA inhibitors) Inhibitors of fat synthesis (Not AC Case inhibitors) 20, 100 and 1000 L 4 to 5 L/ha Not required when used as directed 25

26 Syngenta Contact Details For further information, please contact the Syngenta Technical Product Advice Line: Freecall Freefax or visit our website. For further information please call the Syngenta Technical Product Advice Line on or visit The information contained in this document is believed to be accurate. No responsibility is accepted in respect of this information, save those non-excludable conditions implied by any Federal or State legislation or law of a Territory. Registered trademarks of a Syngenta Group Company. Trademark of a Syngenta Group Company. *Non Syngenta trademark. SB15/290 References Williams C.M.J, Wicks T.J, Akiew S (1985), Potato Diseases in South Australia, South Australian Department of Agriculture. Horne P, De Boer R, Drawford D (2002), Insects and Diseases of Australian Potato Crops, Melbourne University Press. FLAME_SYN2120_08/15