BAYER POTATO GUIDE · Potato Management 2011 Compiled by Dr. D. McClymont (MARMACK CONSULTANTS) and G. Reid (BAYER CROPSCIENCE) 4. PLANTING AND SPACING Plant immediately after disking

Potato ManaPotato Management 2011gement 2011

Compiled by Dr. D. McClymont (MARMACK CONSULTANTS) and G. Reid (BAYER CROPSCIENCE)

POTATOES

1. INTRODUCTION Potatoes are an important food crop in the region. They are best grown between the end of February and beginning of November. Summer crops are expesive to grow and the yields are poor, with lifting being very difficult. The yields respond well to good management 2. CULTIVARS The following varieties grow well in the area and respond to good management. For commercial potato crisps Pimpernel is usually preferred. Because of the vegetative nature of potato multiplication, seed is usually given a categorisation determined by number of generations from the virus tested seed multiplication. The categorisations are-

- VIRUS TESTED SEED - FOUNDATION SEED - AAA - AA - A - B - TABLE WARE

Seed not having these categorisations is 6th generation or more and is NOT recommended for planting. The yield potential and in bred characteristics such as blight tolerance, sprouting and emergence in field diminish with succeeding generations.

BLIGHT YIELDVARIETY MATURITY RESISTANCE SPROUTING YIELD kg/ha POTENTIALAmethyst Very Late Good Quick 50,250 3Baraka Medium Average Slow 56,000 1BP 1 Medium Poor Normal 46,500 7Emerald Late Good Normal 48,000 5Iceberg Short Poor Quick 41,000 9Liseta Medium Early Average Quick 48,000 6Mondial Medium Poor Slow 55,000 2Montclare Very Late Good Quick 49,500 4Pimpernel Late Good Normal 37,500 10Up-to-date Medium Poor Normal 44,250 8

3. SEED When keeping seed for the next planting always better to grade out exactly the correct size of seed required from the previous crop. Setting a high standard from the outset makes for better production in the following year. If a mechanical planter is used then the size and uniformity of the seed is critical. All seed should be dusted with thiram at 20 g/10 kg seed after dipping them for 5 minutes in 200 ml/ 100 l water Kelpac; in each planting furrow also spray imidacloprid (Confidor 70WG®) 3.0 g /100 m row into the furrow ahead of seed placement by hand or machine. Seed can also be pre-treated using pencycuron (Monceren) where Rhizoctonia in soil is a particular problem. Generally there are no problems with sprouting as temperatures will be above the 18ºC - 21ºC minimum required for sprouting.



4. PLANTING AND SPACING Plant immediately after disking in fertilizer and after nematode control measures in rows 0.9 – 1.0 m apart with seed potatoes 20 – 30 cm apart in the row. If a mechanical potato planter is used plant into a small ridge having placed the granular nematicide into the ridge before hand. Apply chemicals either just head or just behind seed being placed. If planting by hand make a furrow in the soil and apply nematicide, insecticide and fungicide to the soil before placing the potato seed. Ridge up afterwards. 5. FERTILIZATION Broadcast 500 kg/ha gypsum and compound fertilizer containing 200 kg/ha N; 350 kg/ha P2O5; 200 K2O and disk in. Start the top dressing programme 3 weeks after germination. Apply in sequence

- 125 kg/ha Ammonium sulphate - 125 kg/ha Ammonium sulphate - 4 l/ha Kelpac - 100 kg/ha Potassium Nitrate - 50 kg/ha Muriate of Potash - 2 l/ha Kelpac - 100 kg/ha Potassium Nitrate - 50 kg/ha Muriate of Potash - 100 kg/ha Potassium Nitrate - 100 kg/ha Potassium Nitrate - 100 kg/ha Potassium Nitrate

The Ammonium Sulphate, Potassium Nitrate, Muriate of Potash and Kelpac can be applied through the irrigation if a centre pivot is being used.

Make sure that the crop gets the equivalent of 2 kg/ha boron in the fertilizer programme – top up with a Solubor spray at planting if required.

Into the planting furrow at planting also apply 500 ml Potatoflo® and 1 l/ha Mollyflo T® together with 1 l/ha Nemablok® making sure they get into contact with the seed material.

6. IRRIGATION

Make sure that the soil is at field capacity at planting and then also plan irrigations so that the soil does not dry out to less than 10 – 15 % below field capacity. Irrigation should take place at least twice per week. 7. WEED CONTROL

BEFORE SPRAYING ALWAYS READ THE CHEMICAL LABEL SEE SECTION 14

Grass Control Pre-plant Incorporated After the fertilizer has been disked in apply EPTC at the following rates depending on the soil clay percentage.

NUTSEGE&

ANNUALactive TRADE SOIL GRASSESingredient NAMES CLAY % RATE /HAEPTC EPTAM® 0 - 16 3.5 l

17 - 30 5.3 l Pre-emergence If a centre pivot is being used for irrigation then trifluralin can, after planting, be sprayed over the ridges in the late afternoon and irrigated in with 15 mm water that night, the rate depending on the soil clay percentage as shown below. EPTC controls annual grasses and nutsedge and trifluralin will control only annual grasses including Rottboellia cochinchinensis.



Soil clay% Rate l/ha0 - 20 1.121 - 30 1.331 - 40 1.641 - 50 1.6

If there is no centre pivot then spray one of the following after planting in 300 l/ha water – irrigate afterwards.

ANNUALactive TRADE SOIL GRASSESingredient NAMES CLAY % RATE L/HAacetochlor HARNESS® 0 - 10 0.5

11 - 20 0.821 - 30 1.031 - 40 1.0

41+ 1.5alachlor LASSO® 0 - 30 2.8 - 3.5

31 - 40 3.5 -4.041+ 3.5 - 4.2

dimethenamid FRONTIER OPTIMA® 0 - 20 0.921 - 30 1.0

31+ 1.2flufenacet TIARA® 0 - 30 400gS-metolachlor DUAL MAGNUM® 0 - 16 0.9

17 - 30 1.031+ 1.2

NB flufenacet does suppress Rottboellia cochinchinensis . In some cases pendimethalin can be applied if R. cochinchinensis is a problem. In 300 l/ha water spray as follows.

ANNUALactive TRADE SOIL GRASSESingredient NAMES CLAY % RATE l/HApendimethalin PROWL® 5 - 20 1.3 - 2.0

21 - 35 2.0 -3.036 -50 2.6 -4.0

If a modicum of broad leaf control is also required with grass control then apply linuron as follows in 300 l/ha water.

ANNUALGRASSES &

active TRADE SOIL B/L WEEDSingredient NAMES CLAY % RATE /HAlinuron AFALON®/LINUREX® 20 - 30 0.75 kg

30+ 1.5 kg Post emergence There are a number of post emergent grass killers that can be sprayed over the top of potatoes. The summary of their rates is given below. The rate used on the day depends on the height and density of the grass weeds. Use higher rates for perennial grasses. Product active ingredient Rate/ha Agil 100 EC® propaquizafop 0.5 – 2.0 l Focus Ultra® cycloxydim 1.2 – 4.0 l Fusilade Super® fluazifop-P-butyl 1.0 – 5.0 l Nabu® sethoxydim 1.5 – 3.0 l Pantera® quizalofop-P-tefuryl 0.75 - 2.0 l Super Gallant® haloxyfop-R-methyl 0.6 - 2.4 l Broadleaf weed control



Pre-emergence For pre-emergent control in 300 l/ha water spray the following according to soil clay percentage. active TRADE SOIL B/L WEEDSingredient NAMES CLAY % RATE l/HAmetribuzin SENCOR® 0 - 10 1.1

11 - 20 1.521 - 35 1.8 - 2.2

Post Emergence For post emergent weed control in 300 l/ha water apply one of the following when the weeds are at the 2 – 4 true leaf stage. active TRADE SOIL B/L WEEDSingredient NAMES CLAY % RATE /HAbentazon BASAGRAN® 2.0- 5.0 llinuron AFALON®/LINUREX® 20 - 30 0.75 kg

30+ 1.5 kgrimsulfuron CATO® 90 g 8. PESTS Before spraying any chemical make sure you have checked on its harvest interval, the withholding period and the re-entry period. Make sure you DO NOT spray any chemical which will leave a toxic residue in the plant after harvest.


Aphids Regular scouting should indicate the present of aphids and then spraying can take place with one of the following applied in 250 l/ha water. Follow up spray as and if required.

Black Maize Beetle The black maize beetle will be suppressed with the granular nematicides that have been applied or will be controlled by imidacloprid (Confidor WG). Caterpillars Various caterpillars attack the crop. These include loopers, army worm etc. Spray as required in 250 l/ha water with one of the following.

ACTIVE INGREDIENT TRADE NAMES acephate ORTHENE® 200 g 30.0 g 500 g acetamiprid MOSPILAN 20 EC® 20 - 30 g 3.0 - 4.5 g 50 - 75 g

thiacloprid CALYPSO® 15-20 ml 12.0 ml 75-100 ml diazinon DIAZINON, DAZ® 120 ml 18.0 ml 300 ml dichlorvos DDVP®, NOGOS® 100 ml 15.0 ml 250 ml dimethoate DIMETHOATE, ROGOR® 75 ml 11.2 ml 187.5 ml

imidacloprid CONFIDOR® 70 WG 90 g 14.0 g 225 g malathion MALATHION 25 WP 500 g 75.0 g 1250 g

MALATHION 50EC 250 ml 37.5 ml 625 ml methamidophos TAMARON® 100 ml 15.0 ml 250 ml methomyl LANNATE

SL®,METHOMEX® 225 ml 33.7 ml 562.5 ml

mevinphos PHOSDRIN 24 EC® 275 ml 41.2 ml 687.5 ml pirimicarb PIRIMOR 50 DG® 100 g 15.0 g 250 g pymetrozine CHESS® 40 g 6.0 g 100 g thiamethoxam

ACTARA 25WG® 80 g 12.0 g 200 g imidacloprid + betacyfluthrin

THUNDER 145 OD®

130 ml 19.0 ml 330 ml

RATE/100 L WATER RATE/HA 15 L KNAPSACK RATE /

spirotetramate MOVENTO SC®



Cutworm Apply one of the following immediately after crop emerges with a blanket spray at 300 l/ha water spray mix.

False Wireworm/ White Grub In the planting furrow apply immediately ahead of seed placement chlorpyriphos (Dursban®) at 4 l/ha or imidacloprid (Confidor WG®) at 300g/ha or imidacloprid + betacyfluthrin (Thunder OD®) at 2 l/ha. Potato Leaf Miner Potato is also attacked by the Serpentine leaf miner (Liriomyza trifolii). Spray at 14 day intervals with one of the following in 250 l/ha water. ACTIVE INGREDIENT TRADE NAMESabamectin AGRIMEC®, ABAMECTIN PLUS® 240 ml 36.0 ml 600 mlcyromazine TRIGARD® 60 g 9.0 g 150 g

RATE/100 L WATER 15 L KNAPSACK RATE/HA

Potato Tuber Moth Potato tuber moth is a serious pest of potato and regular sprays should be undertaken every 14 – 21 days.

If reaped potatoes are to be stored in the field after harvest when a ridge is built over them, spray in 300 l/ha water 1700 ml/ha diflubenzuron (Dimilin®). Spray the potatoes making sure they are adequately covered before ridging up over them. Red Spider Mite Scout for Red spider mite and when it is seen spray at 500 l/ha water with one of the following.

ACTIVE INGREDIENT TRADE NAMES acephate ORTHENE® 200 g 30.0 g 500 g α-cypermethrin FASTAC® 7 ml 1.0 ml 17.5 ml Imidacloprid +β -cyfluthrin THUNDER OD® 130 ml 19.0 ml 330 ml Bacillus thuringiensis DIPEL®, BIOBIT® 200 g 30.0 g 500 g chlorpyrifos DURSBAN®, PYRINEX® 100 ml 15.0 ml 250 ml cypermethrin CYMBUSH®, RIPCORD® 10 ml 1.5 ml 25 ml deltamethrin DECIS FORTE

® 20 ml 3.0 ml 50 ml

dichlorvos DDVP®, NOGOS® 100 ml 15.0 ml 250 ml endosulfan THIODAN SC® 200 ml 30.0 ml 500 ml indoxacarb STEWARD® 35 g 5.2 g 87.5 g λ -cyhalothrin KARATE® 8 ml 1.2 ml 20 ml malathion MALATHION 25 WP 500 g 75.0 g 1250 g

MALATHION 50EC 250 ml 37.5 ml 625 ml methamidophos TAMARON® 100 ml 15.0 ml 250 ml methomyl LANNATE


flubendiamide BELT SC® 30-40 ml 4 ml 75-100 ml


ACTIVE INGREDIENT TRADE NAMES α-cypermethrin FASTAC® 26 ml 3.9 ml 130 ml Imidacloprid + β

-cyfluthrin THUNDER OD ®

100 ml 15.0 ml 300 ml chlorpyrifos DURSBAN®, PYRINEX® 200 ml 30.0 ml 1000 ml cypermethrin CYMBUSH®, RIPCORD® 38 ml 5.7 ml 190 ml deltamethrin DECIS FORTE® 20 ml 3.0 ml 60 ml esfenvalerate SUMI-ALPHA® 20 ml 3.0 ml 100 ml λ -cyhalothrin KARATE® 25 ml 3.7 ml 125 ml profenofos CURACRON® 200 ml 30.0 ml 1000 ml tralomethrin SIBLING®, TRALLATE® 28 ml 4.2 ml 140 ml


ACTIVE INGREDIENT TRADE NAMES acephate ORTHENE® 200 g 30.0 g 500 g flubendiaimde BELT® 30-40 ml 4 ml 75-100 ml bifenthrin TALSTAR® 60 ml 9.0 ml 150 ml carbaryl CARBARYL 200 g 30.0 g 500 g chlorpyrifos DURSBAN ® 60 ml 9.0 ml 150 ml cypermethrin CYMBUSH®, RIPCORD® 70 ml 10.5 ml 175 ml deltamethrin DECIS FORTE® 130 ml 19.5 ml 325 ml esfenvalerate SUMI-ALPHA® 125 ml 18.7 ml 312.5 ml indoxacarb STEWARD® 35 g 5.2 g 87.5 g methamidophos TAMARON® 450 ml 67.5 ml 1125 ml methidathion ULTRACIDE 40EC 100 ml 15.0 ml 250 ml methomyl LANNATE


monocrotophos NUVACRON® 550 ml 82.5 ml 1375 ml profenofos CURACRON® 600 ml 90.0 ml 1500 ml thiodicarb LARVIN® 400 ml 60.0 ml 1000 ml tralomethrin SIBLING®, TRALLATE® 100 ml 15.0 ml 250 ml trichlorfon DIPTEREX 95SP® 300 g 45.0 g 750 g α-cypermethrin FASTAC® 120 ml 18.0 ml 300 ml Imidacloprid + β

-cyfluthrin THUNDER OD® 130 ml 19.0 ml 330 ml λ -cyhalothrin KARATE® 50 ml 7.5 ml 125 ml




9. DISEASES Before spraying any chemical make sure you have checked on its harvest interval, the withholding period and the re-entry period. Make sure you DO NOT spray any chemical which will leave a toxic residue in the plant after harvest.


Routine spray Spraying the crop on a weekly basis with the preventative copper and mancozeb fungicides will take care of most diseases. The recommendations given below are if the infection pressures are too much for the combination and a curative spray is required. A routine spray is given below – one of the copper fungicides with mancozeb or copper with propineb (Antracol ®).

Every third application replace the mancozeb with chlorothalonil (Bravo®) at 3.0 l/ha. Chlorothalonil is very good on both early and late blight and a number of other leaf spots. Bacterial wilt Normally the preventative programme takes care of most bacterial diseases except those that attack during very heavy humidity conditions. For this reason potato production is discouraged during January and February. If attacks do occur the increase the rate of copper fungicide. Black Leg

Black leg (Erwinia carotovora) is a weak pathogen that usually enters the plant or tubers through as a secondary invader after insect or nematode attack. Make sure that nematodes and subsoil insects are well controlled. Black Rot Black rot, (Colletotrichum sp) usually enters as black leg does above. However if a fungicide is sprayed into the planting furrow at planting and the seed is seed dressed with thiram normally the fungus is not seen. Rotation is important – no potato crop in five years controls a great many of these diseases.

ACTIVE INGREDIENT TRADE NAMES abamectin AGRIMEC®, ABAMECTIN PLUS® 240 ml 36.0 ml 600 ml amitraz MITAC® 600 ml 90.0 ml 1500 ml bifenthrin TALSTAR® 160 ml 24.0 ml 400 ml bromopropylate ACAROL® 80 ml 12.0 ml 200 ml chinomethionat MORESTAN® 120 g 18.0 g 300 g chlorphenapyr

CYMITE®, HUNTER® 200 ml 30.0 ml 500 ml diafenthiuron POLO® 320 ml 48.0 ml 800 ml dicofol KELTHANE® 200 ml 30.0 ml 500 ml fenpropathrin MEOTHRIN® 200 ml 30.0 ml 500 ml monocrotophos NUVACRON® 300 ml 45.0 ml 750 ml profenofos CURACRON® 600 ml 90.0 ml 1500 ml propargite OMITE® 400 ml 60.0 ml 1000 ml tetradifon TEDION® 800 ml 119.9 ml 2000 ml spiromesifen OBERON SC® 120 ml 18.0 ml 600 ml


ACTIVE INGREDIENT TRADE NAMES RATE/100 L WATER mancozeb DITHANE

M45 ® 200 g 30.0 g 600 g

PLUS ONE OF FOLLOWING

copper hydroxide KOCIDE®, FUNGURAN OH® KOCIDE 2000®

copper oxychloride

COPPER OXYCHLORIDE 500 75.0 1250 375 g 56.2 g 937.5 g 250 g 37.5 g 625 g

g g g

15 L KNAPSACK RATE/HA

propineb ANTRACOL WP 200 g 30.0 g 600 g



Cercospora and other fungal leaf spots In high humidity and warm conditions Cercospora leaf spot ca be a problem. Regularly spray with a copper fungicide as outlined below every 10 – 14 days, but if the disease stars to move then use one of the other products. Ideally one should not apply more than two sprays 14 days apart of any one of the systemic products listed below.

Early Blight

Normally the preventative programme takes care of most blights except those that attack during very heavy humidity conditions. If the disease does get away, then in 500 l/ha water spray one of the following. Apply a follow up spray 14 days later. Do not stop the preventative programme.

Fusarium tuber rot

ACTIVE INGREDIENT TRADE NAMES RATE/100 L WATER azoxystrobin AMISTAR®,ORTIVA® 200 ml 30.0 ml 500 ml copper hydroxide KOCIDE®, FUNGURAN OH® 500 g 75.0 g 1250 g copper hydroxide KOCIDE 2000® 350 g 52.5 g 875 g copper oxychloride

COPPER OXYCHLORIDE 650 g 97.5 g 1625 g cyproconazole ALTO® 160 ml 24.0 ml 400 ml flusilazole/carbendazim PUNCH C® 200 ml 30.0 ml 500 ml

PUNCH EXTRA® 300 ml 45.0 ml 750 ml flutriafol IMPACT® 320 ml 48.0 ml 800 ml propiconazole TILT® 200 ml 30.0 ml 500 ml propineb ANTRACOL® 200 g 30.0 g 500 g tebuconazole FOLICUR® 200 ml 30.0 ml 500 ml triadimefon BAYLETON 25 EC® 200 ml 30.0 ml 500 ml triadimenol BAYFIDAN 250 EC®, SHAVIT® 200 ml 30.0 ml 500 ml trifloxystrobin TWIST 500 SC® 80 ml 12.0 ml 200 ml


Tebuconazole + trifloxystrobin

NATIVO 300 SC® 240 ml 37.5 ml 600 ml

ACTIVE INGREDIENT TRADE NAMES RATE/100 L WATER azoxystrobin AMISTAR®,ORTIVA® 200 ml 30.0 ml 500 ml chlorothalonil BRAVO ® 1.2 l 200.0 ml 3.0 l cyproconazole ALTO® 160 ml 24.0 ml 400 ml flusilazole/carbendazim PUNCH C® 200 ml 30.0 ml 500 ml

PUNCH EXTRA® 300 ml 45.0 ml 750 ml flutriafol IMPACT® 320 ml 48.0 ml 800 ml iprodione ROVRAL ® 200 ml 30.0 ml 500 ml mancozeb DITHANE

M45 ® 200 g 30.0 g 500 g

penconazole TOPAZ ® 44 ml 6.6 ml 110 ml propiconazole TILT® 200 ml 30.0 ml 500 ml propineb ANTRACOL® 200 g 30.0 g 1000 g tebuconazole FOLICUR® 200 ml 30.0 ml 500 ml Fenamidone/mancozeb NO BLITE WG® 200 g 30.0 g 1000 g triadimenol BAYFIDAN 250 EC®, SHAVIT® 200 ml 30.0 ml 500 ml trifloxystrobin TWIST 500 SC® 40 ml 6.0 g 200 ml




Fusarium tuber rot usually enters as black leg does above. However if a fungicide is sprayed into the planting furrow at planting and the seed is seed dressed with thiram normally the fungus is not seen. Rotation is important – no potato crop in five years controls a great many of these diseases. If there is seen to be a problem or in a short rotation treat the seed with thiophanate methyl + mancozeb (Topsin M®) at 1 kg/100 kg seed. Late Blight

Late blight is the most serious of the potato diseases because of the rapidity of attack. Normally the preventative programme takes care of late blights except an attack during very heavy humidity conditions. If the disease does get away, then in 500 l/ha water spray one of the following. Apply a follow up spray 14 days later. Do not stop the preventative programme.

Powdery Mildew Normally the preventative programme takes care of powdery mildew except an attack during very heavy humidity conditions. Spray one of the following in 250 l/ha water and repeat 14 days later.

ACTIVE INGREDIENT TRADE NAMES RATE/100 L WATER azoxystrobin AMISTAR®,ORTIVA® 40 ml 6.0 ml 100 ml fenamidone/mancozeb NO BLITE® 200 g 119.9 g 1000 g chlorothalonil BRAVO® 800 ml 119.9 ml 2000 ml copper hydroxide KOCIDE®, FUNGURAN OH® 375 g 56.2 g 937.5 g copper hydroxide KOCIDE 2000® 250 g 37.5 g 625 g copper oxychloride

COPPER OXYCHLORIDE 500 g 75.0 g 1250 g cymoxanil/famoxadone TANOS® 40 g 6.0 g 100 g cymoxanil/mancozeb

CURZATE PRO® 600 g 90.0 g 1500 g cymoxanil/propineb MILRAZ® 600 g 90.0 g 1500 g dimethomorph/mancozeb ACROBAT® 800 g 119.9 g 2000 g fosetyl Al/mancozeb MIKAL M® 800 g 119.9 g 2000 g iprovalicarb/propineb MELODY DUO® 450 g 67.5 g 2250 g mancozeb DITHANE M45® 1200 g 179.9 g 3000 g metalaxyl/mancozeb RIDOMIL GOLD® 900 g 134.9 g 2250 g metiram POLYRAM® 1000 g 149.9 g 2500 g propineb ANTRACOL® 800 g 119.9 g 2000 g




Rhizoctonia solani Rhizoctonia solani or black stem can be controlled by the use of the thiophanate seed dressing used above. The spraying of tebuconazole (Tebuzole®, Folicur® or Orius®) at 650 ml/ha into the planting furrow will also help. Scab

Scab does not like acid conditions (pH > 5.2) so be careful when applying lime especially to Varieties such as BP 1. This encourages the scab. The use of Ammonium sulphate as a top dressing source of nitrogen will also help suppress scab. High phosphate and the use of gypsum are also instrumental in controlling scab. The chemical control of scab is very expensive – apply quintozene (Brassicol 75 WP®) at 30- 40 kg/ha as a spray into the planting furrow. Dipping the planting material in thiophanate methyl + mancozeb or thiram helps. Silver scurf The chemical control of scurf is very expensive – apply quintozene (Brassicol 75 WP®) at 30- 40 kg/ha as a spray into the planting furrow. Dipping the planting material in thiophanate methyl + mancozeb or thiram helps. Verticllium wilt Normally the preventative programme takes care of most bacterial diseases except those that attack during very heavy humidity conditions. For this reason potato production is discouraged during January and February. If attacks do occur then increase the rate of copper fungicide. Watery soft rot (Pythium)

ACTIVE INGREDIENT TRADE NAMES RATE/100 L WATER azoxystrobin AMISTAR®,ORTIVA® 200 ml 30.0 ml 500 ml cyproconazole ALTO® 160 ml 24.0 ml 400 ml flusilazole/carbendazim PUNCH C® 200 ml 30.0 ml 500 ml

PUNCH EXTRA® 300 ml 45.0 ml 750 ml flutriafol IMPACT® 320 ml 48.0 ml 800 ml penconazole TOPAZ ® 44 ml 6.6 ml 110 ml propiconazole TILT® 200 ml 30.0 ml 500 ml propineb ANTRACOL® 200 g 30.0 g 500 g tebuconazole FOLICUR® 200 ml 30.0 ml 500 ml iprodione ROVRAL FLO 25

SC® 200 ml 30.0 ml 500 ml

triadimenol BAYFIDAN 250 EC®, SHAVIT® 200 ml 30.0 ml 500 ml trifloxystrobin TWIST 500 SC® 80 ml

12.5 ml 200 ml




This is a disease that comes in at planting. If fungicides are applied for Rhizoctonia control they usually help with the pythium. Viruses (Potato aucuba mosaic potexvirus (PAMV); Potato leaf roll luteovirus (PLRV); Potato S carlavirus PVS); Potato X potexvirus (PVX); Potato Y polyvirus (PVY); Potato X potexvirus (PVX) + Potato Y polyvirus (PVY) – rugose mosaic; Tobacco veinal necrosis virus; Tomato Spotted Wilt tospovirus (TSWV)

Leaf roll virus

Viruses generally come in as a result of insect vector attack. Control the insects and the viruses are seldom if ever seen. Rotation is important and the proximity of other Solanaceous crops such as peppers can have an effect so make sure potatoes are ever planted more than once in 5 years in the same field and that susceptible crops are planted at least 800 m away and preferably down wind from the prevailing wind direction. Make sure that seed is not contaminated and always check on the source. Always seed dress and observe correct hygiene methods when planting, storing or moving seed material. 10. NEMATODES Before spraying or applying any chemical make sure you have checked on its harvest interval, the withholding period and the re-entry period. Make sure you DO NOT spray any chemical which will leave a toxic residue in the plant after harvest.


Nematodes are the pest that can have the largest effect on potatoes. Not only do they affect the roots and prevent tuber formation, they attack the tubers and make them unsightly and their attacks let in a number of devastating diseases that affect both yield and quality. This aspect of potato production can make or break a crop so it is important to get it right.



Meloidogyne javanica is the most important nematode affecting potatoes in this part of the world. Control this and the other kinds are easily killed as the rates for M. javanica are I some cases double what is lethal for the others. There is no ‘magic bullet’ with nematodes so a variety of methods must be used through out the season. The following should be applied into planting furrow before planting using an electrical applicator mounted on the tractor. Hand applications by cup are not recommended. In the case of EDB fumigation, 3 weeks before planting with a suitable applicator apply a blanket application at 40 cm centres across the land applying a minimum of 45 l/ha of the EDB technical grade. Other formulations should be adjusted to give this rate. These applications will have to be followed up with three applications at 4 l/ha a time of either oxamyl (Vydate 310L®) or fenamiphos (Nemacur®) applied as a drench over the plant row. Alternatively 25 l/ha of furfural (Crop Guard®) can be sprayed over the land before the fertilizer is broadcast and this incorporated to a depth of 20 cm. This can be followed up with an over the top application of 25 l/ha of furfural (Crop Guard®) every 2 weeks for the life of the crop. This should be applied immediately before any irrigation. At planting 1 l/ha of Nemablok® should be applied to the planting furrow. 11. FIELD PROCEDURES AND CULTURAL PRACTICES To counter tobacco tuber moth and to prevent green shoulder on the tubers reridge the field when the crop is 25 cm high and again the last time the tractor can enter the land without causing damage. Here a high clearance tractor is an asset. It is often necessary to provide aeration to the soil and keep the ridges soft. The simple attachment on a ripper blade does a fine job (see photo below).

Potatoes should always have a good and even stand. Where there are growth spurts, especially with a yo-yo irrigation ‘Hollow Heart’ may occur. This is not seen from the outside but does lead to complaints on sale. Extreme conditions are conducive to this condition.

12. HARVEST



The harvesting of potatoes is best done with a proper potato lifter; it is well worth the expense in terms of lost seed. Ridges can be cut with an old grader blade welded between two ripper tines but this does not expose the tubers and many can be lost. Near to when the potatoes are to be lifted dig into the ridge at least twice per week and assess the situation When it appears they tubers are ready then make sure the tops are burnt off by spraying in 300 l/ha water 1.5 – 2.0 l/ha paraquat (Gramoxone®) or 3.0 l/ha glufosinate (Basta®). Allow 14 – 21 days between spraying and harvest. The potatoes should be gathered as soon as possible and removed to the shed for grading and then packaging for sale. If the season is dry and the potatoes can be left in the soil after the use of a good quality lifter, spray them with Dimilin as listed above and then reridge. This method does not work if rain or irrigation soaks the potatoes as the chance of rot increases dramatically. Store the potatoes at 12ºC - 15ºC preferably in the dark. Black Heart is a condition that occurs when potatoes are packed to tightly or in sheds where oxygen is excluded. Extremes of temperature (0ºC or 40ºC+) lead to black heart without oxygen exclusion because in these conditions gas diffusion through the tissues is not fact enough.

ADEQUATE AERATION = NO BLACK HEART!

13. YIELD The approximate average yields by variety is given in Section 2 above but yield in the range of 50 - 55 tonnes/ha should be taken as standard.

Documents

BAYER POTATO GUIDE · Potato Management 2011 Compiled by Dr. D. McClymont (MARMACK CONSULTANTS) and G. Reid (BAYER CROPSCIENCE) 4. PLANTING AND SPACING Plant immediately after disking