Ramon's Fabulous Factsheet
Ramon's Fabulous Factsheet

March 2025: Pest Control – Insecticide & Fungicide Spraying

25th March 2025

Hi Folks,
Another massive subject – so I’ll trim it down to the common pests and diseases that we all come across.

PESTS
Let’s identify the pests first:

INSECTS:
Aphids – white/green/black flies; thrips; red spider mite; carrot fly.
DID YOU KNOW? Carrot fly also attacks parsnips, celery and parsley!
Cabbage white butterfly (large white and small white) and their caterpillars.

SLUGS & SNAILS:
Many different types and sizes – all on a mission to destroy your crops, as was evident this past summer!

MAMMALS:
Rabbits, moles, mice, dogs & cats.

It can be soul-destroying to see many months of hard work wiped out by pests, especially when it’s too late to resow. That’s a full 12 months down the pan for the crop affected.

So, what can we do about them?

INSECTS
There are several options:

CHEMICAL CONTROL

There are a plethora of chemical sprays available – Protectants, Contacts and Systemics.
But be aware,the most effective options can also harm beneficial insects, which are vital for pollination. See below for alternatives.

BIOLOGICAL PEST CONTROL

  • Predation – lacewings, ladybirds
  • Parasitism – nematodes
  • Companion planting – the jury’s out, but it works for me
  • IPM Systems – Integrated Pest Management (commonly used in commercial situations)

ORGANIC CONTROL

  • Insecticidal soaps – oil/water emulsions (effective against whitefly)
  • Pyrethrum – made from dried chrysanthemum flower extracts
  • Odour deterrents – neem oil, garlic, peppermint
  • Physical deterrents – soot, wood ash, grease, crop covers, traps
    SLUGS & SNAILS HATE SOOT!
  • Predators – encourage beneficial insects
  • Crop Rotation – including green manures (e.g. Caliente Mustard from greenmanure.co.uk)

IMPORTANT PESTS & DISEASES

Thrips

  • Affects leeks and onions; found between youngest leaf blades
  • Yellow-green in colour; adults up to 2mm long and very mobile
  • Reproduce every 14–30 days; lay up to 80 eggs
  • Control: High-pressure water spray or chemical treatments

Aphids

  • Yellow sticky traps help detect early infestations
  • Olive oil in soapy water suffocates aphids by blocking the pores through which they breathe

Carrot Fly

  • Affects carrots, parsnips, celery, parsley
  • Can overwinter as pupae near last year’s crops; active May–November
  • Adults are 5mm long
  • Control:
    • Chemical sprays
    • Sow resistant varieties
    • Barriers and fine mesh without tears
    • Companion plants
    • Systemic treatments sprayed in the evenings (when carrot fly is most active)

Red Spider Mite

  • Visible under strong magnification
  • Symptoms: Leaves appear dusty; fine webbing forms
  • Adults are 1mm long with 8 legs
  • Conditions: Thrive in hot, dry areas – increase humidity
  • Control: Difficult due to widespread resistance
    • Abamectin (Dynamec) – approx. £15 from The Hydro Bros
    • Phytoseiulus (predatory mite) – approx. £18 from Ladybirdplantcare.co.uk

DISEASES

POTATO BLIGHT

  • Major fungal disease of early and late varieties
  • Affects leaves, stems and tubers
  • ‘Blight Watch’ forecasting service available
  • Control: Chemical, physical and cultural methods
  • Resistant varieties available from most suppliers

LEEK RUST

  • Fungal disease of leeks and other alliums, spread via airborne water droplets
  • Spreads rapidly in warm, humid conditions
  • Disfigures foliage but rarely affects stems
  • Control: Chemical sprays (e.g. Nexles, 50g = £38)
  • Many newer F1 varieties are resistant

ONION MILDEW

  • Fungal disease – doesn’t kill plants but affects bulb size and storage
  • Overwinters in plant debris and soil
  • Spores only released on warm, humid nights
  • Control: Chemicals and cultural practices
    • Signum (500g = £38), Amistar (1L = £62 from Agrigem)

CLUBROOT

  • Soil-borne fungus with no chemical control
  • Affects brassicas and related plants
  • Control tips:
    • Raise soil pH to 6.8
    • Disinfect tools after use
    • Use calcium cyanamide or resistant varieties
    • Mitigation:PERLKA (20% Nitrogen, 50% Lime, 1.5% MgO)
      • KTH – 1kg = £4
      • Gro-Well – 25kg = £60
    • Soil bio-stimulants/mild disinfectants can help

DISEASE RESISTANT VARIETIES

LEEKS:

  • Porbella, Below Zero F1 – rust resistant

BRASSICAS – Clubroot Resistant (available from Simply Seeds):

  • Brussel Sprout Crispus – Early–Mid (£2.79)
  • Cabbage Cordesa – Savoy (£2.29)
  • Cabbage Kilaton – Autumn, good standing (£1.99)
  • Cabbage Lodero – Red (£1.79)
  • Calabrese Monclano – Also mildew resistant (£2.69)
  • Cauliflower Clapton – Autumn (£2.89)
  • Swede Gowrie – Sow between Nov–Feb (Sowseeds)
  • Brussel Sprout Bright – Oct–Nov (Marshalls)

TOMATOES – Blight resistant:

  • Crimson Crush, Mountain Magic

POTATOES:

  • Sarpo Mira – main crop
  • Setanta – red, main crop
  • Cara – white with red eyes, main crop
  • Nicola – yellow, second early
  • Acoustic – second early/main crop; good resistance to disease, drought and extreme weather
    Available from potatohouse.co.uk (£5.60 per 1kg)
    Other varieties: Vitabella (1st early), Colleen (1st early), and many more

PARSNIPS – Canker resistant:

  • Gladiator F1, White Gem

SLUGS & SNAILS

  • Incidences vary by season
  • Best control methods:
    • Nematodes
    • Beer traps
    • Chemicals (Ferric Phosphate)
    • Sheep wool
    • Crushed eggshells

There’s no single solution. In a bad year (like last year), try as many of the above as possible.

I hope this gives you a good basic understanding – so we’ll wrap it there.

Next Month: Growing for Showing

Meanwhile – Keep Healthy, Keep Smiling, Keep Sowing.
Best Wishes,    
Ramon 07594 456292
Plot 21 Silsden Road site