The drops were planned to cover more than 25,000 hectares at Isolated Hill, near the Waima River, and at Kowhai-Swyncombe, near Kaikoura, and have been pushed back until late winter.
An aerial drop of toxic 1080 baits over about 3635ha at Isolated Hill was originally scheduled from May until June but will now take place in the next period of suitable fine weather, an OSPRI TBfree spokeswoman said.
The area has been pre-fed before the 1080 baits were due to be spread.
The operation would cover about 21,460ha.
Green coloured pellets containing 0.15 per cent 1080, or biodegradable sodium fluoroacetate, will be dropped at the rate of two kilograms per hectare, or one bait for every 60 square metres.
In total around 75kg of 1080, or 3gms per hectare, will be spread across both operations.
OSPRI's TBfree programme was targeted to manage and eradicate bovine tuberculosis for farmed cattle and deer, and wild animal populations.
Both operations would target possums as aerial 1080 control is an efficient and cost effective method of knocking their numbers down to low levels needed to eradicate TB from wildlife and declare areas free of the disease.
It is the preferred method of controlling TB in areas such as Kowhai-Swyncombe and Isolated Hill because of the size of the operational areas and terrain.
"Possums eat the forest canopy and prey on native birdlife, including eggs and chicks," the spokeswoman said.
"1080 is extremely effective at controlling other introduced predators, such as ship rats and stoats."
The TB control operations were planned after surveys of wildlife density, information on TB findings in wildlife, and herd testing results.
"Although some operations may be in areas of low apparent TB risk, it is better to err on the side of caution."
Local contractors do most of the possum control programmes in Marlborough using ground based traps and hand laid toxins while aerial operations using 1080 are used to control smaller areas.
Aerial operations were subject to strict safety and monitoring requirements.
Pilots use GPS navigational equipment to ensure the pellets are accurately placed and to avoid identified exclusion areas.
Warning signs are placed at locations during the consent application process.
The public are advised to follow instructions on the warning signs which would remain in place for up to 6-8 months after the last bait applications.
Hunters should not take game from within a two kilometre radius of the operational area if the meat is intended for humans, or pets, or hunt animals within four months after the control work.
The operations have been granted resource consents from the Marlborough District Council, Conservation Department, Ministry of Health, and landowners.
No resource consent was required from Environment Canterbury because the operations are permitted activities.
OSPRI is the not-for-profit primary sector services company formed in 2013 between the Animal Health Board and NAIT to manage TBfree and NAIT programmes.