Pests

: 25 August 2022; Hits: 679

How push-pull technology arrests devastating Fall armyworm, Stemborer & Striga weed

faw pp 003

By George Munene

Developed in 2017 by the International Centre of Insect Physiology and Ecology (icipe), push-pull technology, has been shown to reduce infestation by the devastating fall armyworm by 80 per cent.

This is in addition to mitigating the effects of the equally deleterious Stemborer pest and Striga weed.

First confirmed in 2016 in Nigeria, by 2020, the fall armyworm had caused an average annual loss of 36 per cent in maize production alone; and a total economic loss of $200 million, in Africa.

Striga weed causes 20 to 100 per cent crop losses. It infests 40% of the arable land in sub-Saharan Africa, causing an annual crop loss of $7 to 13 billion.

Stem borers are one of the most serious pests of cereal crops in Africa. Two to four bags of maize are lost out of every 10 that could be harvested.

Originally developed for the control of stemborer pests, the push-pull technology involves intercropping cereal crops with plants, for example, legumes such as desmodium.

Desmodium continuously produces defense odours that repel (push) pests like stemborer and fall armyworm from the target food crop.

The legume releases chemical scents that ward off the pest’s moths, preventing them from laying eggs on the cereal crop. Thus, the chances of the pest populations building up are reduced.

Fodder grass, for instance, Brachiaria, is planted as a border crop, and it releases chemicals that attract (pull) and trap the stemborers/fall armyworm.

This leaves the cereal crop protected from pests.

faw pp 002 1500 1

While it majorly serves to ‘pull’, Brachiaria, also functions as a ‘push’ plant that also repels the fall armyworm pests.

Desmodium also suppresses the parasitic Striga weed.

The legume produces two sets of compounds: one that stimulates the germination of Striga seeds and another that inhibits their growth after germination.

A Conventional Push Pull field with silverleaf desmodium and Napier grass 1

Push-pull also improves soil health as desmodium is an efficient nitrogen-fixing legume.

Additionally, it reduces mycotoxins contamination, a major food safety hazard.

“Even more interesting, we noted that both Desmodium and Brachiaria emit chemicals that attract (pull) natural enemies of the fall armyworm,” says Prof. Toby Bruce of Keele University.

Push-pull technology further helps boost livestock and dairy farming as both Bracharia and Desmodium are high-quality animal fodder plants.

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: 12 August 2022; Hits: 771

KALRO establishes facility to control rust disease causing 80% losses

Marple Kenya 1 615x340

By George Munene

The Kenya Agricultural and Livestock Research Organisation (KALRO) in Njoro has established a diagnostics hub that enables local researchers to identify yellow rust strains-- diseases that reduce grain yields by 30 – 80 per cent-- within two days of collecting samples. This process previously took three to 12 months and was reliant on sending samples overseas.

Historically, the most dangerous and devastating disease on wheat has been stem rust. Wheat yellow rust alone can reduce grain yields by up to 80 per cent and is responsible for annual losses of around 5.47 million tonnes.

The hub is part of MARPLE (Mobile And Real-time PLant disEase) pipeline-- a portable testing lab that provides real-time, point-of-care plant disease diagnostics and surveillance for complex fungal pathogens.

This means that Kenyan researchers can carry out sequencing on location and identify rust strains in as little as two days. The new mobile lab is designed to deliver these results on unstable power supply and without reliance on internet access – both features that make MARPLE accessible for field labs.

“This new diagnostic technique, is a game-changer for us and our country – because we can use it to encourage timely control measures for new races of rust out there”, said KALRO Njoro researcher Dr. Zennah Kosgey at the hub’s launch on Thursday.

Rusts are a type of fungal disease that can infect many crops and spread large distances on the wind. Farmers protect their wheat crops against infection through effective disease management, including planting rust-resistant varieties and applying appropriate fungicides. Over time, however, new rust strains diversify that can overcome resistant varieties, or the fungus itself might become resistant to local fungicide applications.

Early identification of new strains and using this information to plan control strategies before the infection spreads is key to protecting farmers' crops against rust damage.

The Njoro hub marks the third of its kind globally, following the opening of the initial Ethiopian hub and a South Asian hub in Nepal in early 2022.

The platform will improve global rust surveillance as East Africa is a key location for both new rust strains entering the continent and new strains diversifying and moving to the Middle East. Protecting farmers’ harvests relies on understanding this flow of races across continents.

Researchers from the John Innes Centre and International Maize and Wheat Improvement Center (CIMMYT) launched the new Njoro hub by training 17 plant pathologists in the MARPLE pipeline. Participants comprised researchers from both KALRO and the PlantVillage Dream Team.

MARPLE Diagnostics was developed by the Saunders Lab at the John Innes Centre in collaboration with CIMMYT. The project is currently funded by USAID through PlantVillage and BBSRC.

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: 17 June 2022; Hits: 894

Scientists warn of threat from 120 new pests on Kenya's agriculture

Yellow crazy ant

By George Munene

A study conducted on invasive alien pests (IAPs) has identified 120 species not currently present in Kenya but could be introduced and become invasive in the future threatening the economy by impacting on agriculture.

The research conducted by the Centre for Agriculture and Bioscience International (CABI) identified these as the most dangerous IAPs:

Pathogenic organisms

41 pathogenic organisms were found. 10 were present in all countries neighbouring Kenya except S.Sudan.

They included X. citri, C. fimbriata, P. atrosepticum, Faba bean necrotic yellows virus, Ralstonia solanacearum Race 2, Potato spindle tuber viroid (PSTVd), Claviceps fusiformis, Phytophthora colocasiae, Puccinia substriata var. Substriata, and Xanthomonas fragariae.

They all were all judged to have pronounced economic impact and a high likelihood of entry and establishment in Kenya.

85 per cent of the assed pathogens were likely to arrive as contaminants on commodities, especially as seed-borne pathogens. 68 per cent through stowaways if the pathogen could be carried in soil (soil-borne) or by a vector (virus and viroid).

To combat these pathogens scientists suggest as a first course of action to survey for potential presence of the prioritised pathogenic species in Kenya, particularly those that have been reported in neighbouring countries.
Full Participatory Rural Approaches (PRAs) are proposed for those that affect value chains prioritised by Kenya.

Arthropods

The top five species included two species of the whitefly, MEAM1 and MED, the peach fruit fly Bactrocera zonata, the yellow crazy ant Anoplolepis gracilipes, and the Southern armyworm Spodoptera eridania.

70 arthropod species were assessed; 69 insects and one mite.

13 species have already been recorded in neighbouring countries (Ethiopia, Somalia, Sudan, Tanzania, and Uganda)

Six of the species had not been recorded in Africa at the time of the assessment

89 per cent of arthropods were likely to arrive as contaminants on commodities. 16 per cent were likely to arrive as stowaways/hitchhikers, while 6 per cent through unaided good fliers.

Actions to control the prioritised species included conducting full PRAs and surveys or surveillance for their presence or introduction in the country, particularly species reported in neighbouring countries.

In the last decade, Kenya has been particularly affected by new introductions of invasive plant pests that damage cultivated plants.

IAP are pests introduced accidentally or deliberately into a natural environment they are not normally found, with serious negative consequences for their new environment.

The two most “costly” invasive plant pests on the African continent are Pthorimaea Tuta absoluta and Spodoptera frugiperda (fall armyworm). They respectively account for $11.4 B and $9.4 B in losses per annum.

Tuta absoluta, first reported in Kenya in 2013, is now the most destructive invasive tomato pest affecting 41 per cent of tomato farmers with a mean seasonal production loss of 114,000 tonnes.

Lack of or limited resources to update pest lists, organise horizon scanning to prioritise likely pest incursions, and conduct regular surveillances on prioritised pests results in most countries in Sub-Saharan Africa reacting to pest incursions rather than proactively stopping them.

For the original paper visit: Prioritization of invasive alien species with the potential to threaten agriculture and biodiversity in Kenya through horizon scanning

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