VALUABLE DATA shared by CARDI during the SWEET POTATO/CASSAVA WORKSHOP

Cassava Production in Antigua

Varieties:

Sugarloaf, Butter stick, Punt stick. Real Stick, Blue Stick, Maracas Black stick, Pickne Moma, Guyana sweet, Greenstick

CONSTRAINS TO CASSAVA PRODUCTION

  • Abiotic
  • Biotic
  • Management
  • Socioeconomic

Abiotic – temperature, drought, soil fertility, nutrient deficiency, water, light

Plants can adapt to water shortage through various mechanisms such as

  • Decreasing productivity
  • Decrease in growth and biomass production
  • Decrease assimilated portioning
  • Cause poor root development

Biotic – Pests and diseases of cassava

  • Whiteflies
  • Mealybugs
  • Grasshoppers
  • Cassava Hornworm
  • Clinch Bugs
  • Cassava Bacteria Blight
  • Cassava Hornworm:

Larvae feed on young leaves, growing tips and sometimes older leaves and a large population can defoliate the field quickly.

This can result in the loss of the field. Eggs are laid on the upper surface of the leaves and the petioles. The larvae stage lasts for 1 – 2 weeks. Pupation occurs in the soil.

Management:

Cultural –

clean fields, early detection (scout your field regularly), hand-pick when the population is small

Chemical-

Foliar applications using NewBt, Cypro; Carratraxx, Caprid

Cinch Bug

  • This is a sucking insect that operates at the level of the roots.
  • Predispose the plant to nematodes and other soil-borne pathogens

Management:

  • Drench the with an Imidacloprid product.

Shoot fly (Neosilba perezi)

  • Adult lays its egg on the tender leaves or shoot of the plant
  • Egg hatches into a larva
  • Larvae feed on and damage the apical tip of the plant causing stunting and breaking the apical dominance.
  • Increase production of lateral shoots/buds
  • Over-budding and dwarfism occur and decrease the quality of production sticks
  • The larval stage lives inside the stem tissue of the plant. Brown Fras are produced from the feeding and excrement of the larvae.
  • Larva pupates in the soil where it develops into the adult fly

knowledge about the pest and culture interaction, and control methods is important

Cassava Bacterial Blight (Xanthomonas axonopodis pv. Manihotis)

is a serious disease that occurs during the rainy season. Symptoms can include blight, wilting, dieback, and vascular necrosis.

  • Angular necrotic spotting of leaves with chlorotic rings encircling the spots on the underside of the leaves.
  • Gum excaudate along wounds and leaves cross veins. It begins as a sappy golden liquid and hardens to form an amber deposit.
  • Infected leaves may die, and root rot can occur in susceptible varieties
  • Spreads by infected plant material

Super Elongation – Fungal disease

  • Internodes elongation resulting in tall plants with weak stems
  • Curling of leaves

Growth and development of Cassava

Cassava plants have 3 types of roots

  • Fine thin white roots -absorption of water and nutrients
  • Thick roots for anchorage
  • Tuberous roots – storage of carbohydrates

Cassava has 2 distinct growth phases

  • The first growth phase occurs from transplanting to 8 weeks after.
  • Evolves the production of leaves, stems, and thin and thick root systems
  • Tuberization can occur during this stage.
  • The second phase -occurs from week 8 – week 72.

There is rapid growth of leaves and stems and swelling and bulking of tubers

Maximum root development occurs during this phase

Temperatures around 25℃-32℃ assist in this development

Sweet Potato Production:

The Growth Cycle

Sweet potato has 3 distinct growth phases

  1. The Initial Phase-

Slow vine growth and rapid adventitious root growth.

The first 20 days of the adventitious root growth are important as they determine the total number of storage roots formed.

  1. The Intermediate Phase-

There is the rapid growth of vines

increase in leaf area

storage root initiation.

Leaves reach their maximum area by 100 days after planting (DAP),

The deposition of starch within storage roots can occur as early as 8 DAP

Storage root formation can be visible as early as 28 DAP

By 49 DAP, 80% of the storage roots can be identified

  1. Final Phase-

In the final stage, there is bulking of the storage roots, which can reach a maximum after 90 days.

Storage roots enlarge throughout the life of the plant

After 120 days enlargement peaks

It is good to note that most of the growth phases are controlled genetically (i.e. variety)

And (Abiotic) environmentally (i.e. agroecological conditions of the area where the crop is established).

Important insect pests in the Caribbean

are the sweet potato weevils, (Cylas formicarius,

West Indian weevil Euscepes postfasciatus),

white grubs (Phyllophaga spp.),

sweet potato leaf beetle (Typophorus nigritus viridicyaneus)

and the stem borer (Megastes gr,

  • The sweet potato weevil, Cylas forimicarius, is one of the most destructive pests of the sweet potato world
  • Adult females lay eggs in stems or the surface of the roots just under the skin.
  • Eggs hatch and the larvae tunnel into vines and roots where they feed and develop
  • The larval feeding results in tunnels within the sweet potato; often the tunnels are filled excretment.
  • Fully grown larvae pupate and adults emerge from the stems and roots.
  • Due to feeding, the plant produces terpenoids that render the sweet potato unpalatable.

The Bio-stimulants and their usage:

Cassava:

Based on the fact that during the initial stage (between transplanting and 8 weeks. after transplanting) tuberizations can occur, the application of the bio-stimulants should occur during this stage. Three to four applications should be done on a 7-day interval.

Rapid growth of the leaves, stem and bulking, and swelling of the tubers occur during the second stage. This is the stage where fertilizer application should be done. TSP od 12:24:12 can be applied.

I spoke also about the benefits of the 2-node technique vs the 8-10 inches planting material.

Sweet potato

We looked at the main pests and diseases of sweet potato in Antigua and Barbuda and management, it was very interactive. Also, we identified the different growth stages of the sweet potato where we recognized that the adventitious roots determine the number of tuberous roots that are formed, and this occurs during the first 20 days after transplanting. Knowing this and if we want to increase yield then during this time would be the best time to add your bio-stimulants. I suggested that four applications (drenches) seven days apart should be done using Cytokinin, auxins or gibberellins. Fertilizer application could be done around day 49 after transplanting to between day 100 after transplanting.