Edition 87 Thursday 26 November 2015

Transcription

1 Edition 87 Thursday 26 November 2015 This Crop Action contains information on: 1. Prioritising water use in dry conditions 2. Important agrichemical notification 3. FAR events 1. Which crops should take priority if there is insufficient water? With the very dry weather it may be a struggle to keep the irrigation up to all of the crops and a decision may need to be made on which crop to drop out. As the soil dries from the trigger point (TP) toward wilting point, potential yield decreases in a straight line. The slope of this line describes the relative yield decline (RYD). The bigger the potential yields, the greater the relative reductions in yield after TP. The rate of yield loss has been assessed for a range of crops and is described as a percentage of potential yield per mm of soil water deficit (SWD) above the TP. Relative yield decline for a range of crops Crop species % decrease in potential yield for each mm below the trigger point Maize*, oats, potatoes, sweetcorn 0.10% Barley, peas and wheat 0.25% Perennial ryegrass seed 0.28% *maize sensitivity to drought decreases with time because the TP increases as the root system develops. The form of yield loss can change. For instance, early drought stress in barley reduces grain number mostly through the loss of tillers, whereas late drought stress results in small, pinched grain with high screening losses. The yield response to irrigation is the result of avoiding a situation in which the trigger point is exceeded. In round terms, a 50 mm irrigation on a very healthy wheat crop (potential yield 13 t/ha) applied just before trigger point is reached is 13 t/ha x 50 mm x 0.25% = 1.63 t/ha. Assuming irrigation costs $100/ha ($2/mm/ha) and the wheat is worth $300/t, the return would be $480/ha, a net gain of $380/ha. For the same irrigation on a 2.5 t/ha ryegrass seed crop, the yield response would be 2.5 t/ha x 50 mm x 0.28% = 0.35 t/ha. At a value of $2,500/t, the return would be $875/ha, and return net to irrigation of $775/ha. In this example, if there was insufficient water it would pay to irrigate the perennial ryegrass ahead of the wheat.

2 If the soil water content is below the trigger point and there are two warm summer days (equivalent to ET of 10 mm) there will be a potential yield loss of 1 to 3% depending on plant species. Disease management in spring sown barley at GS39 GS49 flag leaf fully emerged to awns emerging (T2) For irrigated crops or early sown disease prone dryland crops consider: Aviator Xpro 0.7 l/ha or Proline 0.2 l/ha + Seguris Flexi 0.3 l/ha or Fandango 0.5 l/ha or Mogul 0.5 l/ha The SDHI option Seguris Flexi would be stronger if the key target diseases were leaf rust and Ramularia leaf spot, whilst the SDHI option based on Aviator Xpro would be stronger on scald and Ramularia leaf spot. Good leaf rust resistance and/or very dry conditions may reduce the value of adding a strobilurin or SDHI with the Proline. The later GS49 timing has the advantage of applying fungicide to the flag leaf sheath, which is un emerged at GS39. However this benefit has to be considered against ensuring that the gap between the two sprays does not exceed four weeks. Dryland crops with lower disease pressure Trials in the Manawatu and Hawkes Bay (and drier inland parts of Southland in previous FAR trials) have shown lower cost fungicide programmes to be more cost effective. In the Manawatu and Hawkes Bay trials there has been no increase in yield from adding other fungicides to a two spray Proline programme in dryland situations. Disease management in autumn sown wheat at GS59 61 ear emergence first flowering (T3) It looks like the dry weather has prevented STB spreading this season in Canterbury there has to be some benefit from the dry weather! In irrigated scenarios FAR research suggests that higher fungicide rates provide better protection against disease, particularly leaf rust. Consider Prosaro 0.6 L/ha or Opus 0.5 L/ha + Comet L/ha. Comet is particularly effective against leaf rust when applied at ear emergence (GS59). Remember that Proline is weaker on leaf rust, hence the use of Prosaro (prothioconazole and tebuconazole), which has been slightly more effective than other mixtures at this timing applied at similar rates. Wetter conditions in Southland may need a different approach Where only one SDHI has been applied prior to T3, wet weather has favoured STB (i.e. Southland), consider mixing the triazole (Opus or Proline at least 75% of the label rate) with Seguris Flexi (isopyrazam) ( L/ha) or use the formulated mixtures of SDHI and triazole Aviator L/ha (prothioconazole and bixafen) or Adexar L/ha (epoxiconazole and fluxapyraxod). Use the higher rates of the SDHI with the susceptible cultivars and earlier sown crops and lower rates with more disease resistant cultivars or later sowings. Where STB and Fusarium sp head infection are the key target diseases, then consider Proline (mixed with tebuconazole e.g. Prosaro for Fusarium sp) as a key ingredient for this spray. Effective control

3 of Fusarium is difficult to achieve, even when the fungicide is applied at the most effective timing (early flowering). In dryland scenarios Consider T3 timing as an optional spray, dependent on rainfall, from flag leaf up until the end of flowering GS69 (anthers visible up the length of the ear). Consider applying fungicide if higher rainfall occurs in this period. Opus alone ( L/ha) or low rate mixtures such as Amistar (0.25 L/ha) + Opus (0.25 L/ha) have been particularly effective to control rusts. Notes: Above rates assume optimum timing of application. Late sprays where disease is at high pressure may require higher rates. In some situations and in some seasons dryland sites may be more equivalent to irrigated sites. In dryland situations monitor rainfall between the key application timings at GS23, 33 and 49 (late tillering awn emergence). Where rainfall is well above the average, consider irrigated strategy options as well as dryland options. 2. Important Agrichemical Notification MPI recently reassessed five insecticides to examine the acceptability of the crops listed on the labels from a dietary intake exposure perspective, and have now released their final decision for these compounds. As a result three compounds: diazinon, fenamiphos and methamidophos cannot be used off label. This means that growers must only use these compounds strictly according to the label and must observe all ACVM & EPA controls. This includes following exact use pattern directions i.e. rate, timing, WHPs and target insect/s etc. Compounds that cannot be used off label: Active Ingredient Diazinon Fenamiphos Trade Names (examples only, check labels for active ingredient) Diazol, Basudin, Dew 600, Diazate, Diazinon 800 EC, Diazonyl 60 EC, Digrub, Gesapon Nemacur, Nematak 400EC, Fenafos, Canyon Methamidophos Metafort 60 SL, Methafos 600 Acephate (trade names Lancer and Orthene) cannot be used off label from 01 July Maldison (trade names Malathion 50EC, Malathion 95) can be used off label, but all EPA controls must be complied with. There are also revised maximum residue limits (MRLs) and WHPs for some crops. The MRLs will be promulgated in July This is to allow labels in the marketplace to be replaced and reduce unintentional MRL non compliance. The new use patterns are available on product labels approved after July A further update will be made at a later stage.

4 3. FAR Events In the coming weeks, FAR will be running major events at our research sites at both Chertsey and Tamahere. Full details can be found on our website. Speakers and topics below: ARIA 2015 Speakers

5 Northern Crop Research Site Field Day Speakers Contact us Nick Poole Rob Craigie Richard Chynoweth Elin Arnaudin NOTE: This publication is copyright to the Foundation for Arable Research ( FAR ) and may not be reproduced or copied in any form whatsoever without FAR s written permission. This publication is intended to provide accurate and adequate information relating to the subject matters contained in it and is based on information current at the time of publication. Information contained in this publication is general in nature and not intended as a substitute for specific professional advice on any matter and should not be relied upon for that purpose. No endorsement of named products is intended nor is any criticism of other alternative, but unnamed products. It has been prepared and made available to all persons and entities strictly on the basis that FAR, its researchers and authors are fully excluded from any liability for damages arising out of any reliance in part or in full upon any of the information for any purpose. All previous Crop Actions and other publications can be viewed on the FAR website: contact the FAR Office if you would like to unsubscribe from Crop Action, or change your address.

6 Brassica Integrated Pest Management (IPM) Field Visit The brassica IPM field visit will be facilitated by Dr Paul Horne (IPM Technologies Pty). It will be held in South Canterbury at Haden Batty s farm. Informal discussion will cover: How to use IPM in seed and forage brassicas Beneficial insect identification IPM monitoring and decision-making Chemical options available If you have any queries or would like to confirm your attendance please contact Abie Horrocks: Phone: or abie.horrocks@plantandfood.co.nz Tuesday 8 December pm 3.00 pm South Canterbury Meet at corner of Orari Back Rd and Bennett Rd