Papaya (Paw Paw) Horticulture

Consulting in papaya plays a vital role in maintaining good plant health throughout the life of the crop, whether it be to identify and monitor pest and disease species or manage fertiliser programs to ensure productivity is maximized. There are numerous pest species and diseases that affect papaya production, some capable of devastating a crop. Papaya plantations are monitored on a weekly basis to ensure we are able to accurately capture the level of pest or disease pressure and can act quickly to prevent economic damage occurring to that crop. Two of the most significant pests causing damage in papaya in north Queensland are Fruit Spotting Bugs (Amblypelta nitida) and Two-spotted mites (Tetranychus urticae). Fruit Spotting Bugs are a major and frequent pest in this region and are more frequent in plantations adjacent to areas of rainforest. Adults and nymphs of this pest feed by piercing and sucking sap primarily from the growing point of the tree, which becomes distorted and stunted. This attack appears to be more prominent in the early growth stage of the crop and severe attacks may kill young trees. Leaf stems have elongated sunken areas and the stems fail to reach their full length. Damage may also be inflicted on the fruit, resulting in dark, sunken lesions.

Two spotted mites are another pest species that can cause significant damage to papaya crops. Mites feed by sucking out the contents of plant cells and this feeding can cause extensive leaf, flower and fruit damage. Leaf damage is characterised by yellow mottled or stippled areas, primarily on the underside of leaves. Damage first appears near the main leaf veins. Naturally existing predators such as the small black lady beetle Stethorus spp. can help to control mite populations, however other predatory mites such as Amblyseius spp. and Phytoseiulus persimilis can be purchased from reputable breeding companies to be released as a biological control agent to help minimise mite damage in the papaya crop. Once these pest and diseases are identified in the crop, recommendations are made to eradicate them.

Tully, QLD

Problems with consistency in fruit set resulted in a trial with various nutrient treatments in combination with Petrik products being set out in 2008. After soil testing and amendments with lime and dolomite, the entire field was planted on 3 t/ha of chicken manure and fertigation was set up to deliver individual applications to 12 plots of 3 rows each. The experimental design was an incomplete factorial. Nitrogen was applied to one third of the plots at 100, 250 and 500 kg/ha/yr split into 14 day applications resulting in 4, 10 and 20 kg/ha/week of N to the four plots in each treatment. The base program was sulfate of ammonia with additional nitrogen as urea being applied to the higher N treatments. Bxd was applied to a half of the plots on Jan 21 2008 at the full rate of 1 kg/ha. On this same date the nutrition treatments commenced. All treatments were grower applied. Setbest, Impulse boron and Biolator and manganese foliar were applied at 28 day intervals to half of the plot from Feb 11 2008. A fruit count was carried out on April 21 2008.

This trial produced some dramatic visual and statistical evidence. Nitrogen did have an impact upon productivity however there was a significant nitrogen biology interaction. The low nitrogen treatment produced the highest fruit count when used in conjunction with the Bxd Biology and Setbest foliar. This however was the lowest producing treatment without this support. Considering only the treatments without biological support results in the conclusion that 20 kg/ha/14 days of N is required to produce a viable crop. Consideration of the biology treatments however completely changes this. Overall, comparing treated to untreated plots Bxd resulted in a 50.9% higher fruit count. Impulse Boron was the next most significant treatment at 39.9% and Setbest improved fruit count by 19.4%. 500 kg/ha/yr of nitrogen in comparison lifted the fruit count by only 15.8%. The higher nitrogen plots also had some negative effects including more undesirable vegetative growth and higher fruit spotting bug incidence.

Papaya Treated With Petrik Bxd

No Petrik Bxd - No Fruit Set

The full results of the trial including:
Treatment schedule - list and quantities of products included in the trial; Fruit count for each treatment schedule; Percentage increase in fruit count per treatment schedule can be found by viewing our PDF document.

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